Improving salt tolerance and mitigating senescence in the presence of high salinity are crucial for sustaining agricultural productivity.Previous research has demonstrated that hydrogen peroxide(H_(2)O_(2)),specifical...Improving salt tolerance and mitigating senescence in the presence of high salinity are crucial for sustaining agricultural productivity.Previous research has demonstrated that hydrogen peroxide(H_(2)O_(2)),specifically H_(2)O_(2)derived from roots and mediated by the respiratory burst oxidase homolog(NADPH),plays a significant role in regulating ion and plant hormone homeostasis in glycophytic plants,such as Arabidopsis.However,the extent to which root-derived H_(2)O_(2)fulfils similar functions in halophytic plants remains uncertain.Therefore,our study aimed to explore the potential contribution of root-sourced H_(2)O_(2)in delaying leaf senescence induced by high salinity,utilizing seashore paspalum as a model halophytic plant.The application of the NADPH-oxidase inhibitor DPI,coupled with a series of leaf senescence analyses,we revealed that root-derived H_(2)O_(2)significantly retards salt-induced leaf senescence.Furthermore,through the application of hormone analysis,lipidomics,ionomics,Non-invasive Micro-test Technology(NMT),and transcriptomics,we established that NADPH-dependent H_(2)O_(2)induced by salt stress in the roots was indispensable for maintaining the balance of the aging hormone,jasmonic acid(JA),and sodium ion homeostasis within this halophytic plant.Finally,by utilizing AtrbohD Arabidopsis mutants and virus-induced gene silencing(VIGs)in Paspalum vaginatum,we demonstrated the pivotal role played by root-sourced H_(2)O_(2)in upholding JA homeostasis and regulating JA-triggered leaf senescence in P.vaginatum.This study offers novel insights into the mechanisms that govern plant leaf senescence and its response to salinity-induced stress.展开更多
Traditional agricultural systems have contributed to food and livelihood security. Rice-crab coculture （RC） is an important eco-agricultural process in rice production in northern China. Recognizing the soil fertili...Traditional agricultural systems have contributed to food and livelihood security. Rice-crab coculture （RC） is an important eco-agricultural process in rice production in northern China. Recognizing the soil fertility in RC may help develop novel sustainable agriculture. Soil carbohydrates are important factors in determining soil fertility in different culture modes. In this study, soil carbohydrates were analyzed under three different culture modes including rice monoculture （RM）, conventional rice-crab coculture （CRC） and organic rice-crab coculture （ORC）. Results showed that the contents of soil organic carbon and carbohydrates were significantly higher in the ORC than those in RM. The increasing effect was greater with increased organic manure. Similar tendency was found in CRC, but the overall effect was less pronounced compared with ORC. Carbohydrates were more Sensitive to RC mode and manure amendment than soil organic carbon. Compare to RM, the （Gal＋Man）/（Ara＋Xyl） ratio decreased in all the RC modes, indicating a relative enrichment in plant-derived carbohydrates due to the input of crab feed and manure. While the increasing （Gal＋Man）/（Ara＋Xyl） ratio in ORC modes with increased organic manure suggested that crab activity and metabolism induced microbially derived carbohydrates accumulation. The lower GluN/MurA ratio in ORC indicated an enhancement of bacteria contribution to SOM turnover in a short term. The findings reveal that the ORC mode could improve the quantity and composition of soil carbohydrates, effectively, to ensure a sustainable use of paddy soil.展开更多
Maqu County is located in the northeast Qinghai-Tibetan Plateau, and it is the main watershed for the Yellow River. The ecosystem there is extremely vulnerable and sensitive to climate change and human activities, whi...Maqu County is located in the northeast Qinghai-Tibetan Plateau, and it is the main watershed for the Yellow River. The ecosystem there is extremely vulnerable and sensitive to climate change and human activities, which have caused significant deterioration of the eco-environment in this region. In order to restore the ecological environment, a government project to restore the grazing areas to grassland was implemented in Maqu County in early 2004. This study evaluates the effects of that restoration project on land use and land cover change （LUCC）, and explores the driving forces of LUCC in Maqu County. In the study we used Landsat images obtained in 1989, 2004, 2009, and 2014 to establish databases of land use and land cover. Then we derived LUCC information by overlaying these layers using GIS software. Finally, we analyzed the main forces responsible for LUCC. The results showed that forests, high-coverage grasslands, and marshes experienced the most significant decreases during 1989–2004, by 882.8 ha, 35,250.4 ha, and 2,753.4 ha, respectively. However, moderate- and low-coverage grasslands and sand lands showed the opposite trend, increasing by 12,529.7 ha, 25,491.0 ha, and 577.5 ha, respectively. LUCC in 2004–2009 showed that ecological degradation slowed compared with 1989？2004. During 2009–2014, high- and moderate-coverage grasslands increased obviously, but low-coverage grasslands, marshes, unused lands, sand lands, and water areas showed the opposite trend. These results suggested that the degradation of the eco-environment was obvious before 2009, showing a decrease in the forests, grasslands, and water areas, and an increase in unused lands. The ecological degradation was reversed after 2009, as was mainly evidenced by increases in high- and mod-erate-coverage grasslands, and the shrinkage rate of marshes decreased obviously. These results showed that the project of restoring grazing lands to grassland had a positive effect on the LUCC. Other major factors that influence the LUCC include increasing temperature, variation in the seasonal frozen soil environment, seasonal overgrazing, and pest and rodent damage.展开更多
There is a lack of quantitative assessments available on the effect of agricultural intensification on soil aggregate distribution and microbial properties. Here, we investigated how short-term nitrogen(N) intensifica...There is a lack of quantitative assessments available on the effect of agricultural intensification on soil aggregate distribution and microbial properties. Here, we investigated how short-term nitrogen(N) intensification induced changes in aggregate size distribution and microbial properties in a soil of a hot moist semi-arid region(Bangalore, India). We hypothesised that N intensification would increase the accumulation of macroaggregates > 2 mm and soil microbial biomass and activity, and that the specific crop plant sowed would influence the level of this increase. In November 2016, surface(0–10 cm) and subsurface(10–20 cm) soil samples were taken from three N fertilisation treatments, low N(50 kg N ha-1), medium N(75 and 100 kg N ha-1 for finger millet and maize, respectively),and high N(100 and 150 kg N ha-1 for finger millet and maize, respectively). Distribution of water-stable aggregate concentrations,carbon(C) and N dynamics within aggregate size class, and soil microbial biomass and activity were evaluated. The high-N treatment significantly increased the concentration of large macroaggregates in the subsurface soil of the maize crop treatment, presumably due to an increased C input from root growth. Different N fertilisation levels did not significantly affect C and N concentrations in different aggregate size classes or the bulk soil. High-N applications significantly increased dehydrogenase activity in both the surface soil and the subsurface soil and urease activity in the surface soil, likely because of increased accumulation of enzymes stabilised by soil colloids in dry soils. Dehydrogenase activity was significantly affected by the type of crop, but urease activity not. Overall, our results showed that high N application rates alter large macroaggregates and enzyme activities in surface and subsurface soils through an increased aboveground and corresponding belowground biomass input in the maize crop.展开更多
Five-year trials （2011-2015） were accomplished in a continuous field experiment conducted at the Production and Research Station in Balcyny. The experiment was set up on a luvisol medium soil, derived from light loa...Five-year trials （2011-2015） were accomplished in a continuous field experiment conducted at the Production and Research Station in Balcyny. The experiment was set up on a luvisol medium soil, derived from light loam with the objective of evaluating the response of two winter triticale varieties （Pigmej and Cyrkon） to cultivation without protection （O）, chemical weed control （H） and combined protection against weeds and fungi （HF）. Comparisons were made in two crop sequence systems： cultivation of winter triticale varieties in a 6-field crop rotation and cultivation in a 19-23-year-long monoculture. The results showed that the plant sequence system significantly differentiated the response of winter triticale varieties to the applied levels of field protection. Significantly higher grain yield gains of the winter triticale varieties in response to the application of herbicides or herbicides with fungicides were obtained in the monoculture than in the crop rotation. In the crop rotation, a higher increase in yields induced by the applied plant protection treatments was achieved by the variety Cyrkon. In the monoculture, the response of both varieties to the herbicides applied was nearly identical, while the combined application of herbicides and fungicides raised the yields of var. Pigmej higher than those of var. Cyrkon. Overall for the plant protection levels, var. Cyrkon yielded higher than var. Pigmej by 18.1% more in the crop rotation and by 26.9% in the monoculture. At the same time, var. Cyrkon demonstrated a weaker response to being grown in the monoculture than var. Pigmej did. The average yield of the former was reduced by 21.1%, whereas the latter yielded 26.6% less grain.展开更多
This study aimed to understand bark thickness variations of Araucaria angustifolia(Bertol.)Kuntze trees growing in natural forest remnants in southern Brazil,and their relationship with quantitative and qualitative at...This study aimed to understand bark thickness variations of Araucaria angustifolia(Bertol.)Kuntze trees growing in natural forest remnants in southern Brazil,and their relationship with quantitative and qualitative attributes.Bark thickness must be accurately estimated in order to determine timber volume stocks.This is an important variable for the sustainable management and conservation of araucaria forests.In spite of its importance and visibility,bark thickness variations have not been evaluated for this key species in southern Brazil.A total of 104 trees were selected,and their qualitative and quantitative attributes such as diameter at breast height(D_(BH)),height(H),crown base height(C_(BH)),crown length(C_(L)),social position(S_(P)),stoniness(S_(T)),position on the relief(P_(R)),vitality(V_T)and branch arrangement(B_(A))were measured.The trees were categorized into two groups:red bark or gray bark.Regression analysis and artificial neural networks(ANN)were used for modelling bark thickness.The results indicate that:(1)bark thickness showed good correlation to D_(BH),with 0.76 as coefficient of determination(RS_P),0.540 as Mean Absolute Error(M_(AE))and 22.4 root-meansquare error in percentage(R_(MSE%));(2)the trend changed according to bark colour,with significant differences for the intersection(_0–Pr>F:p=0.0124)and slope(β_(1)–Pr>F:p=0.0126)of bark thickness curves between groups;(3)the highest correlation of bark thickness was found with:D_(BH)(ρ=0.88),H(ρ=0.58),C_(BH)(ρ=0.46),S_(P)(ρ=-0.52),and B_(A)(ρ=-0.32);(4)modelling with ANN confirmed high adjustment(R^(2)=0.99)and accuracy(R_(MSE%)=3.0)of the estimates.ANN is an efficient and robust technique for the modelling of various qualitative and quantitative attributes commonly used in forest mensuration.The effective use of ANN to estimate araucaria bark in natural forests reinforces its potential,besides the possibility of application for other forest species.展开更多
In Tanzania, the phenology and seasonal variations of the yields of different rice cultivars have rarely been studied, especially under fully-irrigated conditions. A trial was conducted to identify the most suitable c...In Tanzania, the phenology and seasonal variations of the yields of different rice cultivars have rarely been studied, especially under fully-irrigated conditions. A trial was conducted to identify the most suitable calendar for rice production in Tanzania under fully-irrigated conditions. Four popular rice cultivars, NERICA1, Wahiwahi, IR64 and TXD306, were transplanted monthly from January to December 2011. The four cultivars recorded similarly higher or lower yields than the annual means when transplanted in July （0.50-0.57 kg/m2） and April （0.07-0.31 kg/m2）. A yield-ranking analysis showed that plants transplanted in July was the most productive while those transplanted in April was the least productive, and also revealed a yield-seasonality for irrigated rice in Tanzania, a low-yield season （April-May）, a high-yield season （June-August）, and an unstable-yield season （September-March）. These yield seasons would appear to be closely linked to seasonal temperature variations. When transplanted in April-May, plants were exposed to very low temperatures between panicle initiation and flowering, apparently reducing yield through cold-induced sterility. Those transplanted in June-August prolonged their growth under relatively low temperatures and increased yield through increasing biomass production. In September- March, yield levels varied greatly due to the shortened phenological growth durations at higher temperatures. We conclude that under fully-irrigated conditions in Tanzania, rice should be transplanted in July to ensure the maximum production and yield stability. The yield-seasonality suggests that implementing measures to protect plants from low and high temperature stress at critical phenological stages may allow year-round rice production under fully-irrigated conditions in Tanzania.展开更多
Cabbage is today an economically important crop grown in more than 90 countries around the world. Production is constantly threatened by pests including the cabbage webworm, Hellula undalis (F.) (Lepidoptera: Pyralida...Cabbage is today an economically important crop grown in more than 90 countries around the world. Production is constantly threatened by pests including the cabbage webworm, Hellula undalis (F.) (Lepidoptera: Pyralidae) which just one or two larvae can cause severe damage by infesting the growing points or shoots of young plants. Hellula undalis is difficult to control by the use of chemical insecticides. The establishment of effective biological control is needed. The parasitoid species Pristomerus pallidus (Hymenoptera: Ichneumonidae: Cremastinae) was recorded for the first time in Senegal on larvae of Hellula undalis from cabbage fields infested with H. undalis. Laboratory observed parasitism was 7.4%. This is the first record of Pristomerus pallidus parasitizing Hellula undalis from Senegal. Furthermore, studies on the potential regulation of Hellula undalis under controlled and field conditions need to be evaluated for utilizing this parasitoid as a biocontrol agent against the cabbage webworm. .展开更多
Crop pests are a permanent threat to horticultural production. Several control methods are recommended for their control, including biological control. This method based on the use of natural enemies is not well estab...Crop pests are a permanent threat to horticultural production. Several control methods are recommended for their control, including biological control. This method based on the use of natural enemies is not well established. The objective of this study was to assess the diversity and abundance of natural enemies of crop pests. A survey of crops associated with pests was carried out on 144 fields in southern Senegal to measure the diversity and abundance of natural enemies of various crop pests, determine the native parasitoid complex and assess parasitism rates. Ecological indices were calculated to assess the diversity of natural enemies. A total of 25 natural enemy species were identified, including 15 parasitoids and 10 predators. Predatory Hemiptera and Parasitoid Hymenoptera were high biodiversity. The parasitism rates vary between 0 and 50% depending on the abundance of pests and parasitoid species. Knowledge of the diversity of natural enemies and the understanding of trophic interactions with pests are important in the development of biological crop protection in order to preserve resilience in agroecosystems.展开更多
Riverdikes are habitats that must be revegetated quickly in order to prevent soil erosion. With increasing pressure to improve the cost efficiency of management, new revegetation techniques suitable under reduced mowi...Riverdikes are habitats that must be revegetated quickly in order to prevent soil erosion. With increasing pressure to improve the cost efficiency of management, new revegetation techniques suitable under reduced mowing frequencies are required. Imperata cylindrica (L.) P. Beauv. is an important component of grasslands in several Asian countries. Its vigorous rhizome elongation should be useful for quickly covering bare ground. We tested the effects of sowing (at two densities), transplanting, and sodding of I. cylindrica on plant cover and species richness of established vegetation over 3 years. The sodding and high-density sowing treatments achieved the most rapid increase in cover, followed by low-density sowing, transplanting, and the control. By year 2, however, the cover in the low- and high-density sowing treatments was similar. The sodding treatment had significantly fewer species than the other treatments in year 1. Between years 1 and 2 and years 2 and 3, the total number of species increased in the transplanting treatment, whereas it decreased in the sodding and two sowing treatments. Accordingly, if stabilization and erosion control are the priority, introduction of I. cylindrica using sod and high-density sowing is the most suitable method. If immediate green-up is not imperative, low-density sowing is likely to provide available resources for new seedlings of diverse species to become established, allowing the introduction of representative species in semi-natural grasslands. More research will be needed on the effects of introducing diverse species (e.g., sowing seed mixtures) that include I. cylindrica on the resulting floristic composition.展开更多
Phosphorus loading and measurement is of concern on lands where biosolids have been applied. Traditional soil testing for plant-available P may be inadequate for the accurate assessment of P loadings in a regulatory e...Phosphorus loading and measurement is of concern on lands where biosolids have been applied. Traditional soil testing for plant-available P may be inadequate for the accurate assessment of P loadings in a regulatory environment as the reported levels may not correlate well with environmental risk. In order to accurately assess potential P runoff and leaching, as well as plant uptake, we must be able to measure organic P mineralized by the biotic community in the soil. Soils with varying rates of biosolid application were evaluated for mineralized organic P during a 112-day incubation using the difference between P measured using a rapid-flow analyzer (RFA) and an axial flow Varian ICP-OES. An increase in the P mineralized from the treated soils was observed from analysis with the Varian ICP-OES, but not with the RFA. These results confirm that even though organic P concentrations have increased due to increasing biosolid application, traditional soil testing using an RFA for detection, would not accurately portray P concentration and potential P loading from treated soils.展开更多
Waxy maize with its pure amylopectin starch is the staple food of many ethnic minorities in hilly regions of Southeast Asia （SEA）. A combination of waxy and quality protein maize （QPM） traits would improve the qua...Waxy maize with its pure amylopectin starch is the staple food of many ethnic minorities in hilly regions of Southeast Asia （SEA）. A combination of waxy and quality protein maize （QPM） traits would improve the quality of protein of waxy maize for human consumption. Double recessive waxy-QPM （wx-o2） genotypes had been generated from Southern Chinese material by haploid induction of crosses heterozygous for the two quality traits with an absolutely conserved waxy type and an improved amino acid profile. The vitreous kernel trait （due to the additional modifier genes present in QPM） was lost in the wx-o2 plant material; this may be due to the waxy mutation, this is anyhow desirable for acceptance as waxy maize is preferred due to its soft grains. The content of the quality limiting amino acid lysine was greatly increased in double recessive wx-o2 genotypes compared to standard waxy maize, but still with a high variation among genotypes for future improvement. Conclusively, it was indeed possible to combine two grain quality mutations successfully within one genotype and prototypes of double quality wx-o2 are available now to contribute to meet human requirements in essential amino acids and thus reduce malnutrition in various regions of Asia.展开更多
Background:Forests perform various important ecosystem functions that contribute to ecosystem services.In many parts of the world,forest management has shifted from a focus on timber production to multi-purpose forest...Background:Forests perform various important ecosystem functions that contribute to ecosystem services.In many parts of the world,forest management has shifted from a focus on timber production to multi-purpose forestry,combining timber production with the supply of other forest ecosystem services.However,it is unclear which forest types provide which ecosystem services and to what extent forests primarily managed for timber already supply multiple ecosystem services.Based on a comprehensive dataset collected across 150 forest plots in three regions differing in management intensity and species composition,we develop models to predict the potential supply of 13 ecosystem services.We use those models to assess the level of multifunctionality of managed forests at the national level using national forest inventory data.Results:Looking at the potential supply of ecosystem services,we found trade-offs(e.g.between both bark beetle control or dung decomposition and both productivity or soil carbon stocks)as well as synergies(e.g.for temperature regulation,carbon storage and culturally interesting plants)across the 53 most dominant forest types in Germany.No single forest type provided all ecosystem services equally.Some ecosystem services showed comparable levels across forest types(e.g.decomposition or richness of saprotrophs),while others varied strongly,depending on forest structural attributes(e.g.phosphorous availability or cover of edible plants)or tree species composition(e.g.potential nitrification activity).Variability in potential supply of ecosystem services was only to a lesser extent driven by environmental conditions.However,the geographic variation in ecosystem function supply across Germany was closely linked with the distribution of main tree species.Conclusions:Our results show that forest multifunctionality is limited to subsets of ecosystem services.The importance of tree species composition highlights that a lack of multifunctionality at the stand level can be compensated by managing forests at the landscape level,when stands of complementary forest types are combined.These results imply that multi-purpose forestry should be based on a variety of forest types requiring coordinated planning across larger spatial scales.展开更多
Traditionally, soil-testing laboratories have used a variety of methods to determine soil organic matter, yet they lack a practical method to predict potential N mineralization/immobilization from soil organic matter....Traditionally, soil-testing laboratories have used a variety of methods to determine soil organic matter, yet they lack a practical method to predict potential N mineralization/immobilization from soil organic matter. Soils with high micro-bial activity may experience N immobilization (or reduced net N mineralization), and this issue remains unresolved in how to predict these conditions of net mineralization or net immobilization. Prediction may become possible with the use of a more sensitive method to determine soil C:N ratios stemming from the water-extractable C and N pools that can be readily adapted by both commercial and university soil testing labs. Soil microbial activity is highly related to soil organic C and N, as well as to water-extractable organic C (WEOC) and water-extractable organic N (WEON). The relationship between soil respiration and WEOC and WEON is stronger than between respiration and soil organic C (SOC) and total organic N (TON). We explored the relationship between soil organic C:N and water-extractable organic C:N, as well as their relationship to soil microbial activity as measured by the flush of CO2 following rewetting of dried soil. In 50 different soils, the relationship between soil microbial activity and water-extractable organic C:N was much stronger than for soil organic C: N. We concluded that the water-extractable organic C:N was a more sensitive measurement of the soil substrate which drives soil microbial activity. We also suggest that a water-extractable organic C:N level > 20 be used as a practical threshold to separate those soils that may have immobilized N with high microbial activity.展开更多
In addition to their value as cereal grains, wheat (Triticum aestivum L.) and triticale (× Triticosecale Wittmack) are important cool-season annual forages and cover crops. Yearling steer (Bos taurus) performance...In addition to their value as cereal grains, wheat (Triticum aestivum L.) and triticale (× Triticosecale Wittmack) are important cool-season annual forages and cover crops. Yearling steer (Bos taurus) performance was compared in the spring following autumn establishment as for age cover crops after soybean [Glycine max (L.) Merr.] grain harvest. Replicated pastures (0.4 ha) were no-till seeded in three consecutive years into soybean stubble in autumn, fertilized, and grazed the following spring near Ithaca, NE, USA. Each pasture (n = 3) was continuously stocked in spring with four yearling steers (380 ± 38 kg) for 17, 32, and 28 d in 2005, 2006, and 2007, respectively. In 2005, average daily gain (ADG) for steers grazing triticale exceeded the ADG for wheat by 0.31 kghd<sup>-1</sup>d<sup>-1</sup>. In 2006, wheat ADG exceeded that for triticale by 0.12 kghd<sup>-1</sup>d<sup>-1</sup>. In 2007, steers grazing wheat lost weight, while steers grazing triticale gained 0.20 kghd<sup>-1</sup>d<sup>-1</sup>. Based on the 3-year average animal gains valued at $1.32 kg<sup>-1</sup>, mean net return ($ ha<sup>-1</sup> yr<sup>-1</sup>) was $62.15 for triticale and $22.55 for wheat. Since these grazed cover crops provide ecosystem services in addition to forage, grazing could be viewed as a mechanism for recovering costs and adds additional value to the system. Based on this 3-year grazing trial, triticale was superior to wheat and likely will provide the most stable beef yearling performance across years with variable weather for the western Cornbelt USA.展开更多
Soil microbial diversity is extremely vulnerable to fertilization,which is one of the main anthropogenic activities associated with global changes.Yet we know little about how and why soil microbial diversity responds...Soil microbial diversity is extremely vulnerable to fertilization,which is one of the main anthropogenic activities associated with global changes.Yet we know little about how and why soil microbial diversity responds to fertilization across contrasting local ecological contexts.This knowledge is fundamental for predicting changes in soil microbial diversity in response to ongoing global changes.We analyzed soils from ten 20-year field fertilization(organic and/or inorganic)experiments across China and found that the national-scale responses of soil bacterial diversity to fertilization are dependent on ecological context.In acidic soils from regions with high precipitation and soil fertility,inorganic fertilization can result in further acidification,resulting in negative impacts on soil bacterial diversity.In comparison,organic fer-tilization causes a smaller disturbance to soil bacterial diversity.Despite the overall role of environmental contexts in driving soil microbial diversity,a small group of bacterial taxa were found to respond to fer-tilization in a consistent way across contrasting regions throughout China.Taxa such as Nitrosospira and Nitrososphaera,which benefit from nitrogen fertilizer addition,as well as Chitinophagaceae,Bacilli,and phototrophic bacteria,which respond positively to organic fertilization,could be used as bioindicators for soil fertility in response to fertilization at the national scale.Overall,our work provides new insights into the importance of local environmental context in determining the responses of soil microbial diver-sity to fertilization,and identifies regions with acidic soils wherein soil microbial diversity is more vul-nerable to fertilization at the national scale.展开更多
The regulation of water regime in the soil is the most important task in semi-humid climate with not even precipitation distribution conditions. Reduced or minimum tillage may change soil hydrological properties. The ...The regulation of water regime in the soil is the most important task in semi-humid climate with not even precipitation distribution conditions. Reduced or minimum tillage may change soil hydrological properties. The objectives of this study were to investigate the possibilities to manage soil water regime during the whole soil tillage system for sugar beet, which are especially sensitive for water deficit or abundance. Five field experiments were carried out at the Experimental Station of the Lithuanian University of Agriculture (Aleksandras Stulginskis University since 2011) (54°52'N, 23°49'E) during 1995-2010. The soil of the experiments was silty loam Luvisol. In this study we highlighted the reduction of primary soil tillage from deep annual soil ploughing to shallow ploughing, deep and shallow cultivation and no till, comparison of soil ploughing and subsoiling, presowing ploughed or unploughed soil tillage with different cultivators—S-tine, complex, rotary and others, soil compressing with Cambridge and spur rollers before and after sugar beet sowing investigations. According to the results of experiments, reduction of primary soil tillage conserved soil water. The highest storage of soil water in spring was observed in non-reversibly tilled or not tilled soil. Subsoiling led higher water infiltration rate, and top layer of subsoiled soil consisted less moisture content than ploughed. Sugar beet seedbed moisture mostly depended on soil tillage intensity and depth. Presowing rotary tilling was the top tillage method in the case of water preservation in ploughed or unploughed soil. Soil compressing with rollers mostly had negative or low influence on light loam Luvisol moisture content. Rolling with Cambridge roller effected on more rapid water transport from deeper to top sugar beet seedbed layers and higher evaporation rate.展开更多
Background:Meadow fescue(Schedonorus pratensis(Huds.)P.Beauv.)is a reemerging pasture grass for temperate regions of North America.One disadvantage of this species is its lack of tolerance to frequent defoliation at l...Background:Meadow fescue(Schedonorus pratensis(Huds.)P.Beauv.)is a reemerging pasture grass for temperate regions of North America.One disadvantage of this species is its lack of tolerance to frequent defoliation at low residual sward heights.This experiment was designed to conduct one cycle of selection and evaluation for persistence under frequent defoliation.Methods:The experiment included four locations with intensive grazing:two on silt loam soils and two on loamy sand soils.A fifth location was managed with frequent mowing to a 5-cm residual sward height,approximately 12-15 mowings per year.One cycle of selection was conducted with a population size of 1000 plants and 20 plants were selected for survivorship and vigor.Seed of all selected populations was evaluated at all five selection locations.Results:Gains were made in all eight populations,both due to increases in endophyte infection frequency and genetic gains associated with improved host genotypes.Selection was successful on both silt loam and loamy sand soils,but none of those gains were realized on the alternate soil type.Selection was successful at two of the four grazing farms,the two located on silt loam soils,but these gains were not realized on the farms with loamy sand soils or under the frequent mowing method of defoliation.Conclusions:Selection for tolerance to intensive grazing should be conducted under grazing conditions and selection for adaptation to both sandy and silt loam soils will require a more complex and imaginative selection scheme.展开更多
Nutrients in agricultural runoff may cause offsite environmental impacts.The objective of this investigation was to examine nutrient transport by overland sheet flow on sites containing swine slurry.Data examined in t...Nutrients in agricultural runoff may cause offsite environmental impacts.The objective of this investigation was to examine nutrient transport by overland sheet flow on sites containing swine slurry.Data examined in this study was collected during field rainfall simulation tests conducted on cropland sites in southeast Nebraska,USA.Inflow was added to the top of experimental plots in four successive increments to simulate runoff rates occurring at greater downslope distances.Runoff rates on the experimental sites ranged from 2.3 to 21.2 L min^(-1) and maximum equivalent downslope distances varied from 5 to 108 m.Phosphorus(P)and nitrogen(N)transport rates were found to increase in a linear fashion with runoff rate.Hypothesis testing using the student’s t-test affirmed the prediction that a linear equation,calibrated for site specific conditions,can be used to relate nutrient transport rates to runoff rates.P and N transport rates were thought to be influenced by(a)the quantity of nutrients released by swine slurry at a particular runoff rate and(b)the amount of overland sheet flow available to transport the released nutrients.If nutrient transport rates can be linked to runoff rates,it may be possible to extrapolate experimental results obtained from small plots to greater downslope distances.Existing process-based models used to route overland sheet flow along hillslopes on upland areas could also be modified to include nutrient constituents.展开更多
Background:Three water balance models were used to quantify water use efficiency on 71 golf courses in the United States.The golf courses were separated into five geographic regions.Methods:The United States Golf Asso...Background:Three water balance models were used to quantify water use efficiency on 71 golf courses in the United States.The golf courses were separated into five geographic regions.Methods:The United States Golf Association(USGA),Tipping-Bucket(TB),and Agro-IBIS(AG)water balance models were used to estimate golf course water requirements.Actual water use was divided by the water requirement from each model to generate three water efficiency scores for each golf course(WESUSGA,WESTB,and WESAG).Results:The mean WESUSGA was 1.16,the mean WESTB was 1.25,and the mean WESAG was 1.17.Thus,golf courses in this study used between 16%and 25%more water than predicted by the three models.The coefficients of variation of WESUSGA,WESTB,and WESAG were all 0.45 or higher,indicating that some golf courses used significantly more or less water than predicted by the models.Rooting depth,irrigated area,and soil texture were especially important modeling parameters for the golf course water requirement calculations.Conclusions:While onsite evaluation should still be carried out to verify the assumptions made by the water balance models,the models are promising tools to quickly identify golf course superintendents who are likely to be using water efficiently and those who could use less.展开更多
基金supported by the Project funded by the Natural Science Foundation of Hainan Province(Grant No.322QN248)the National Natural Science Foundation of China(Grant Nos.32401488,32060409,32371782 and 32460358)+3 种基金the Innovational Fund for Scientific and Technological Personnel of Hainan Province(Grant No.KJRC 2023C21)the Hainan High-level Talents Project(Grant No.321RC475)Collaborative Innovation Center Project of Nanfan and High-Efficiency Tropical Agriculture in Hainan University(XTCX2022NYB08)Collaborative Innovation Center Project of Ecological Civilization in Hainan University(XTCX2022STC10).
文摘Improving salt tolerance and mitigating senescence in the presence of high salinity are crucial for sustaining agricultural productivity.Previous research has demonstrated that hydrogen peroxide(H_(2)O_(2)),specifically H_(2)O_(2)derived from roots and mediated by the respiratory burst oxidase homolog(NADPH),plays a significant role in regulating ion and plant hormone homeostasis in glycophytic plants,such as Arabidopsis.However,the extent to which root-derived H_(2)O_(2)fulfils similar functions in halophytic plants remains uncertain.Therefore,our study aimed to explore the potential contribution of root-sourced H_(2)O_(2)in delaying leaf senescence induced by high salinity,utilizing seashore paspalum as a model halophytic plant.The application of the NADPH-oxidase inhibitor DPI,coupled with a series of leaf senescence analyses,we revealed that root-derived H_(2)O_(2)significantly retards salt-induced leaf senescence.Furthermore,through the application of hormone analysis,lipidomics,ionomics,Non-invasive Micro-test Technology(NMT),and transcriptomics,we established that NADPH-dependent H_(2)O_(2)induced by salt stress in the roots was indispensable for maintaining the balance of the aging hormone,jasmonic acid(JA),and sodium ion homeostasis within this halophytic plant.Finally,by utilizing AtrbohD Arabidopsis mutants and virus-induced gene silencing(VIGs)in Paspalum vaginatum,we demonstrated the pivotal role played by root-sourced H_(2)O_(2)in upholding JA homeostasis and regulating JA-triggered leaf senescence in P.vaginatum.This study offers novel insights into the mechanisms that govern plant leaf senescence and its response to salinity-induced stress.
基金supported by the National Natural Science Foundation of China (41101274 and 41101275)
文摘Traditional agricultural systems have contributed to food and livelihood security. Rice-crab coculture （RC） is an important eco-agricultural process in rice production in northern China. Recognizing the soil fertility in RC may help develop novel sustainable agriculture. Soil carbohydrates are important factors in determining soil fertility in different culture modes. In this study, soil carbohydrates were analyzed under three different culture modes including rice monoculture （RM）, conventional rice-crab coculture （CRC） and organic rice-crab coculture （ORC）. Results showed that the contents of soil organic carbon and carbohydrates were significantly higher in the ORC than those in RM. The increasing effect was greater with increased organic manure. Similar tendency was found in CRC, but the overall effect was less pronounced compared with ORC. Carbohydrates were more Sensitive to RC mode and manure amendment than soil organic carbon. Compare to RM, the （Gal＋Man）/（Ara＋Xyl） ratio decreased in all the RC modes, indicating a relative enrichment in plant-derived carbohydrates due to the input of crab feed and manure. While the increasing （Gal＋Man）/（Ara＋Xyl） ratio in ORC modes with increased organic manure suggested that crab activity and metabolism induced microbially derived carbohydrates accumulation. The lower GluN/MurA ratio in ORC indicated an enhancement of bacteria contribution to SOM turnover in a short term. The findings reveal that the ORC mode could improve the quantity and composition of soil carbohydrates, effectively, to ensure a sustainable use of paddy soil.
基金the funding received from the Natural Science Foundation of China (41301003, 41371026, and 31470480)the Technology of the People's Republic of China (No. 2013CB956000)
文摘Maqu County is located in the northeast Qinghai-Tibetan Plateau, and it is the main watershed for the Yellow River. The ecosystem there is extremely vulnerable and sensitive to climate change and human activities, which have caused significant deterioration of the eco-environment in this region. In order to restore the ecological environment, a government project to restore the grazing areas to grassland was implemented in Maqu County in early 2004. This study evaluates the effects of that restoration project on land use and land cover change （LUCC）, and explores the driving forces of LUCC in Maqu County. In the study we used Landsat images obtained in 1989, 2004, 2009, and 2014 to establish databases of land use and land cover. Then we derived LUCC information by overlaying these layers using GIS software. Finally, we analyzed the main forces responsible for LUCC. The results showed that forests, high-coverage grasslands, and marshes experienced the most significant decreases during 1989–2004, by 882.8 ha, 35,250.4 ha, and 2,753.4 ha, respectively. However, moderate- and low-coverage grasslands and sand lands showed the opposite trend, increasing by 12,529.7 ha, 25,491.0 ha, and 577.5 ha, respectively. LUCC in 2004–2009 showed that ecological degradation slowed compared with 1989？2004. During 2009–2014, high- and moderate-coverage grasslands increased obviously, but low-coverage grasslands, marshes, unused lands, sand lands, and water areas showed the opposite trend. These results suggested that the degradation of the eco-environment was obvious before 2009, showing a decrease in the forests, grasslands, and water areas, and an increase in unused lands. The ecological degradation was reversed after 2009, as was mainly evidenced by increases in high- and mod-erate-coverage grasslands, and the shrinkage rate of marshes decreased obviously. These results showed that the project of restoring grazing lands to grassland had a positive effect on the LUCC. Other major factors that influence the LUCC include increasing temperature, variation in the seasonal frozen soil environment, seasonal overgrazing, and pest and rodent damage.
基金financially supported by German Research Foundation(DFG)the Indian Department of Biotechnology(DBT)
文摘There is a lack of quantitative assessments available on the effect of agricultural intensification on soil aggregate distribution and microbial properties. Here, we investigated how short-term nitrogen(N) intensification induced changes in aggregate size distribution and microbial properties in a soil of a hot moist semi-arid region(Bangalore, India). We hypothesised that N intensification would increase the accumulation of macroaggregates > 2 mm and soil microbial biomass and activity, and that the specific crop plant sowed would influence the level of this increase. In November 2016, surface(0–10 cm) and subsurface(10–20 cm) soil samples were taken from three N fertilisation treatments, low N(50 kg N ha-1), medium N(75 and 100 kg N ha-1 for finger millet and maize, respectively),and high N(100 and 150 kg N ha-1 for finger millet and maize, respectively). Distribution of water-stable aggregate concentrations,carbon(C) and N dynamics within aggregate size class, and soil microbial biomass and activity were evaluated. The high-N treatment significantly increased the concentration of large macroaggregates in the subsurface soil of the maize crop treatment, presumably due to an increased C input from root growth. Different N fertilisation levels did not significantly affect C and N concentrations in different aggregate size classes or the bulk soil. High-N applications significantly increased dehydrogenase activity in both the surface soil and the subsurface soil and urease activity in the surface soil, likely because of increased accumulation of enzymes stabilised by soil colloids in dry soils. Dehydrogenase activity was significantly affected by the type of crop, but urease activity not. Overall, our results showed that high N application rates alter large macroaggregates and enzyme activities in surface and subsurface soils through an increased aboveground and corresponding belowground biomass input in the maize crop.
文摘Five-year trials （2011-2015） were accomplished in a continuous field experiment conducted at the Production and Research Station in Balcyny. The experiment was set up on a luvisol medium soil, derived from light loam with the objective of evaluating the response of two winter triticale varieties （Pigmej and Cyrkon） to cultivation without protection （O）, chemical weed control （H） and combined protection against weeds and fungi （HF）. Comparisons were made in two crop sequence systems： cultivation of winter triticale varieties in a 6-field crop rotation and cultivation in a 19-23-year-long monoculture. The results showed that the plant sequence system significantly differentiated the response of winter triticale varieties to the applied levels of field protection. Significantly higher grain yield gains of the winter triticale varieties in response to the application of herbicides or herbicides with fungicides were obtained in the monoculture than in the crop rotation. In the crop rotation, a higher increase in yields induced by the applied plant protection treatments was achieved by the variety Cyrkon. In the monoculture, the response of both varieties to the herbicides applied was nearly identical, while the combined application of herbicides and fungicides raised the yields of var. Pigmej higher than those of var. Cyrkon. Overall for the plant protection levels, var. Cyrkon yielded higher than var. Pigmej by 18.1% more in the crop rotation and by 26.9% in the monoculture. At the same time, var. Cyrkon demonstrated a weaker response to being grown in the monoculture than var. Pigmej did. The average yield of the former was reduced by 21.1%, whereas the latter yielded 26.6% less grain.
基金This study is supported by the Graduate Program in Forest Engineering of the Santa Catarina State University(UDESC)the Santa Catarina Research Foundation(FAPESC+3 种基金2017TR1762,2017TR639,2019TR816)the Brazilian National Council for Scientifi c and Technological Development(CNPq313887/2018-7)the Coordination for the Improvement of Higher Education Personnel(CAPES).
文摘This study aimed to understand bark thickness variations of Araucaria angustifolia(Bertol.)Kuntze trees growing in natural forest remnants in southern Brazil,and their relationship with quantitative and qualitative attributes.Bark thickness must be accurately estimated in order to determine timber volume stocks.This is an important variable for the sustainable management and conservation of araucaria forests.In spite of its importance and visibility,bark thickness variations have not been evaluated for this key species in southern Brazil.A total of 104 trees were selected,and their qualitative and quantitative attributes such as diameter at breast height(D_(BH)),height(H),crown base height(C_(BH)),crown length(C_(L)),social position(S_(P)),stoniness(S_(T)),position on the relief(P_(R)),vitality(V_T)and branch arrangement(B_(A))were measured.The trees were categorized into two groups:red bark or gray bark.Regression analysis and artificial neural networks(ANN)were used for modelling bark thickness.The results indicate that:(1)bark thickness showed good correlation to D_(BH),with 0.76 as coefficient of determination(RS_P),0.540 as Mean Absolute Error(M_(AE))and 22.4 root-meansquare error in percentage(R_(MSE%));(2)the trend changed according to bark colour,with significant differences for the intersection(_0–Pr>F:p=0.0124)and slope(β_(1)–Pr>F:p=0.0126)of bark thickness curves between groups;(3)the highest correlation of bark thickness was found with:D_(BH)(ρ=0.88),H(ρ=0.58),C_(BH)(ρ=0.46),S_(P)(ρ=-0.52),and B_(A)(ρ=-0.32);(4)modelling with ANN confirmed high adjustment(R^(2)=0.99)and accuracy(R_(MSE%)=3.0)of the estimates.ANN is an efficient and robust technique for the modelling of various qualitative and quantitative attributes commonly used in forest mensuration.The effective use of ANN to estimate araucaria bark in natural forests reinforces its potential,besides the possibility of application for other forest species.
基金Supporting Service Delivery Systems of Irrigated Agriculture (TANRICE,2008–2012)
文摘In Tanzania, the phenology and seasonal variations of the yields of different rice cultivars have rarely been studied, especially under fully-irrigated conditions. A trial was conducted to identify the most suitable calendar for rice production in Tanzania under fully-irrigated conditions. Four popular rice cultivars, NERICA1, Wahiwahi, IR64 and TXD306, were transplanted monthly from January to December 2011. The four cultivars recorded similarly higher or lower yields than the annual means when transplanted in July （0.50-0.57 kg/m2） and April （0.07-0.31 kg/m2）. A yield-ranking analysis showed that plants transplanted in July was the most productive while those transplanted in April was the least productive, and also revealed a yield-seasonality for irrigated rice in Tanzania, a low-yield season （April-May）, a high-yield season （June-August）, and an unstable-yield season （September-March）. These yield seasons would appear to be closely linked to seasonal temperature variations. When transplanted in April-May, plants were exposed to very low temperatures between panicle initiation and flowering, apparently reducing yield through cold-induced sterility. Those transplanted in June-August prolonged their growth under relatively low temperatures and increased yield through increasing biomass production. In September- March, yield levels varied greatly due to the shortened phenological growth durations at higher temperatures. We conclude that under fully-irrigated conditions in Tanzania, rice should be transplanted in July to ensure the maximum production and yield stability. The yield-seasonality suggests that implementing measures to protect plants from low and high temperature stress at critical phenological stages may allow year-round rice production under fully-irrigated conditions in Tanzania.
文摘Cabbage is today an economically important crop grown in more than 90 countries around the world. Production is constantly threatened by pests including the cabbage webworm, Hellula undalis (F.) (Lepidoptera: Pyralidae) which just one or two larvae can cause severe damage by infesting the growing points or shoots of young plants. Hellula undalis is difficult to control by the use of chemical insecticides. The establishment of effective biological control is needed. The parasitoid species Pristomerus pallidus (Hymenoptera: Ichneumonidae: Cremastinae) was recorded for the first time in Senegal on larvae of Hellula undalis from cabbage fields infested with H. undalis. Laboratory observed parasitism was 7.4%. This is the first record of Pristomerus pallidus parasitizing Hellula undalis from Senegal. Furthermore, studies on the potential regulation of Hellula undalis under controlled and field conditions need to be evaluated for utilizing this parasitoid as a biocontrol agent against the cabbage webworm. .
文摘Crop pests are a permanent threat to horticultural production. Several control methods are recommended for their control, including biological control. This method based on the use of natural enemies is not well established. The objective of this study was to assess the diversity and abundance of natural enemies of crop pests. A survey of crops associated with pests was carried out on 144 fields in southern Senegal to measure the diversity and abundance of natural enemies of various crop pests, determine the native parasitoid complex and assess parasitism rates. Ecological indices were calculated to assess the diversity of natural enemies. A total of 25 natural enemy species were identified, including 15 parasitoids and 10 predators. Predatory Hemiptera and Parasitoid Hymenoptera were high biodiversity. The parasitism rates vary between 0 and 50% depending on the abundance of pests and parasitoid species. Knowledge of the diversity of natural enemies and the understanding of trophic interactions with pests are important in the development of biological crop protection in order to preserve resilience in agroecosystems.
文摘Riverdikes are habitats that must be revegetated quickly in order to prevent soil erosion. With increasing pressure to improve the cost efficiency of management, new revegetation techniques suitable under reduced mowing frequencies are required. Imperata cylindrica (L.) P. Beauv. is an important component of grasslands in several Asian countries. Its vigorous rhizome elongation should be useful for quickly covering bare ground. We tested the effects of sowing (at two densities), transplanting, and sodding of I. cylindrica on plant cover and species richness of established vegetation over 3 years. The sodding and high-density sowing treatments achieved the most rapid increase in cover, followed by low-density sowing, transplanting, and the control. By year 2, however, the cover in the low- and high-density sowing treatments was similar. The sodding treatment had significantly fewer species than the other treatments in year 1. Between years 1 and 2 and years 2 and 3, the total number of species increased in the transplanting treatment, whereas it decreased in the sodding and two sowing treatments. Accordingly, if stabilization and erosion control are the priority, introduction of I. cylindrica using sod and high-density sowing is the most suitable method. If immediate green-up is not imperative, low-density sowing is likely to provide available resources for new seedlings of diverse species to become established, allowing the introduction of representative species in semi-natural grasslands. More research will be needed on the effects of introducing diverse species (e.g., sowing seed mixtures) that include I. cylindrica on the resulting floristic composition.
文摘Phosphorus loading and measurement is of concern on lands where biosolids have been applied. Traditional soil testing for plant-available P may be inadequate for the accurate assessment of P loadings in a regulatory environment as the reported levels may not correlate well with environmental risk. In order to accurately assess potential P runoff and leaching, as well as plant uptake, we must be able to measure organic P mineralized by the biotic community in the soil. Soils with varying rates of biosolid application were evaluated for mineralized organic P during a 112-day incubation using the difference between P measured using a rapid-flow analyzer (RFA) and an axial flow Varian ICP-OES. An increase in the P mineralized from the treated soils was observed from analysis with the Varian ICP-OES, but not with the RFA. These results confirm that even though organic P concentrations have increased due to increasing biosolid application, traditional soil testing using an RFA for detection, would not accurately portray P concentration and potential P loading from treated soils.
文摘Waxy maize with its pure amylopectin starch is the staple food of many ethnic minorities in hilly regions of Southeast Asia （SEA）. A combination of waxy and quality protein maize （QPM） traits would improve the quality of protein of waxy maize for human consumption. Double recessive waxy-QPM （wx-o2） genotypes had been generated from Southern Chinese material by haploid induction of crosses heterozygous for the two quality traits with an absolutely conserved waxy type and an improved amino acid profile. The vitreous kernel trait （due to the additional modifier genes present in QPM） was lost in the wx-o2 plant material; this may be due to the waxy mutation, this is anyhow desirable for acceptance as waxy maize is preferred due to its soft grains. The content of the quality limiting amino acid lysine was greatly increased in double recessive wx-o2 genotypes compared to standard waxy maize, but still with a high variation among genotypes for future improvement. Conclusively, it was indeed possible to combine two grain quality mutations successfully within one genotype and prototypes of double quality wx-o2 are available now to contribute to meet human requirements in essential amino acids and thus reduce malnutrition in various regions of Asia.
基金funded through the project‘Bio Holz’(grant no.01LC1323A)in the funding program‘Research for the Implementation of the National Biodiversity Strategy(F&U NBS)’by the German Federal Ministry for Education and Research(BMBF)and the German Federal Agency for Nature Conservation(Bf N)with funds provided by the German Federal Ministry for the Environment,Nature Conservation,Building and Nuclear Safety(BMUB)supported by the DFG Priority Program 1374‘Infrastructure-Biodiversity-Exploratories’。
文摘Background:Forests perform various important ecosystem functions that contribute to ecosystem services.In many parts of the world,forest management has shifted from a focus on timber production to multi-purpose forestry,combining timber production with the supply of other forest ecosystem services.However,it is unclear which forest types provide which ecosystem services and to what extent forests primarily managed for timber already supply multiple ecosystem services.Based on a comprehensive dataset collected across 150 forest plots in three regions differing in management intensity and species composition,we develop models to predict the potential supply of 13 ecosystem services.We use those models to assess the level of multifunctionality of managed forests at the national level using national forest inventory data.Results:Looking at the potential supply of ecosystem services,we found trade-offs(e.g.between both bark beetle control or dung decomposition and both productivity or soil carbon stocks)as well as synergies(e.g.for temperature regulation,carbon storage and culturally interesting plants)across the 53 most dominant forest types in Germany.No single forest type provided all ecosystem services equally.Some ecosystem services showed comparable levels across forest types(e.g.decomposition or richness of saprotrophs),while others varied strongly,depending on forest structural attributes(e.g.phosphorous availability or cover of edible plants)or tree species composition(e.g.potential nitrification activity).Variability in potential supply of ecosystem services was only to a lesser extent driven by environmental conditions.However,the geographic variation in ecosystem function supply across Germany was closely linked with the distribution of main tree species.Conclusions:Our results show that forest multifunctionality is limited to subsets of ecosystem services.The importance of tree species composition highlights that a lack of multifunctionality at the stand level can be compensated by managing forests at the landscape level,when stands of complementary forest types are combined.These results imply that multi-purpose forestry should be based on a variety of forest types requiring coordinated planning across larger spatial scales.
文摘Traditionally, soil-testing laboratories have used a variety of methods to determine soil organic matter, yet they lack a practical method to predict potential N mineralization/immobilization from soil organic matter. Soils with high micro-bial activity may experience N immobilization (or reduced net N mineralization), and this issue remains unresolved in how to predict these conditions of net mineralization or net immobilization. Prediction may become possible with the use of a more sensitive method to determine soil C:N ratios stemming from the water-extractable C and N pools that can be readily adapted by both commercial and university soil testing labs. Soil microbial activity is highly related to soil organic C and N, as well as to water-extractable organic C (WEOC) and water-extractable organic N (WEON). The relationship between soil respiration and WEOC and WEON is stronger than between respiration and soil organic C (SOC) and total organic N (TON). We explored the relationship between soil organic C:N and water-extractable organic C:N, as well as their relationship to soil microbial activity as measured by the flush of CO2 following rewetting of dried soil. In 50 different soils, the relationship between soil microbial activity and water-extractable organic C:N was much stronger than for soil organic C: N. We concluded that the water-extractable organic C:N was a more sensitive measurement of the soil substrate which drives soil microbial activity. We also suggest that a water-extractable organic C:N level > 20 be used as a practical threshold to separate those soils that may have immobilized N with high microbial activity.
文摘In addition to their value as cereal grains, wheat (Triticum aestivum L.) and triticale (× Triticosecale Wittmack) are important cool-season annual forages and cover crops. Yearling steer (Bos taurus) performance was compared in the spring following autumn establishment as for age cover crops after soybean [Glycine max (L.) Merr.] grain harvest. Replicated pastures (0.4 ha) were no-till seeded in three consecutive years into soybean stubble in autumn, fertilized, and grazed the following spring near Ithaca, NE, USA. Each pasture (n = 3) was continuously stocked in spring with four yearling steers (380 ± 38 kg) for 17, 32, and 28 d in 2005, 2006, and 2007, respectively. In 2005, average daily gain (ADG) for steers grazing triticale exceeded the ADG for wheat by 0.31 kghd<sup>-1</sup>d<sup>-1</sup>. In 2006, wheat ADG exceeded that for triticale by 0.12 kghd<sup>-1</sup>d<sup>-1</sup>. In 2007, steers grazing wheat lost weight, while steers grazing triticale gained 0.20 kghd<sup>-1</sup>d<sup>-1</sup>. Based on the 3-year average animal gains valued at $1.32 kg<sup>-1</sup>, mean net return ($ ha<sup>-1</sup> yr<sup>-1</sup>) was $62.15 for triticale and $22.55 for wheat. Since these grazed cover crops provide ecosystem services in addition to forage, grazing could be viewed as a mechanism for recovering costs and adds additional value to the system. Based on this 3-year grazing trial, triticale was superior to wheat and likely will provide the most stable beef yearling performance across years with variable weather for the western Cornbelt USA.
基金funding from the National Key R&D Program of China (2016YFD0300802)the Field Station Consortium Program of The Chinese Academy of Sciences (KFJ-SWYW035)+1 种基金funding from the National Key R&D Program (2019YFC1520700)Manuel Delgado-Baquerizo is supported by a Ramón y Cajal grant from the Spanish Ministry of Science and Innovation (RYC2018-025483-I)
文摘Soil microbial diversity is extremely vulnerable to fertilization,which is one of the main anthropogenic activities associated with global changes.Yet we know little about how and why soil microbial diversity responds to fertilization across contrasting local ecological contexts.This knowledge is fundamental for predicting changes in soil microbial diversity in response to ongoing global changes.We analyzed soils from ten 20-year field fertilization(organic and/or inorganic)experiments across China and found that the national-scale responses of soil bacterial diversity to fertilization are dependent on ecological context.In acidic soils from regions with high precipitation and soil fertility,inorganic fertilization can result in further acidification,resulting in negative impacts on soil bacterial diversity.In comparison,organic fer-tilization causes a smaller disturbance to soil bacterial diversity.Despite the overall role of environmental contexts in driving soil microbial diversity,a small group of bacterial taxa were found to respond to fer-tilization in a consistent way across contrasting regions throughout China.Taxa such as Nitrosospira and Nitrososphaera,which benefit from nitrogen fertilizer addition,as well as Chitinophagaceae,Bacilli,and phototrophic bacteria,which respond positively to organic fertilization,could be used as bioindicators for soil fertility in response to fertilization at the national scale.Overall,our work provides new insights into the importance of local environmental context in determining the responses of soil microbial diver-sity to fertilization,and identifies regions with acidic soils wherein soil microbial diversity is more vul-nerable to fertilization at the national scale.
基金ob-tained through postdoctoral fellowship(No.004/38)funded by the European Union Structural Funds project“Postdoctoral Fellowship Implementation in Lithuania”.
文摘The regulation of water regime in the soil is the most important task in semi-humid climate with not even precipitation distribution conditions. Reduced or minimum tillage may change soil hydrological properties. The objectives of this study were to investigate the possibilities to manage soil water regime during the whole soil tillage system for sugar beet, which are especially sensitive for water deficit or abundance. Five field experiments were carried out at the Experimental Station of the Lithuanian University of Agriculture (Aleksandras Stulginskis University since 2011) (54°52'N, 23°49'E) during 1995-2010. The soil of the experiments was silty loam Luvisol. In this study we highlighted the reduction of primary soil tillage from deep annual soil ploughing to shallow ploughing, deep and shallow cultivation and no till, comparison of soil ploughing and subsoiling, presowing ploughed or unploughed soil tillage with different cultivators—S-tine, complex, rotary and others, soil compressing with Cambridge and spur rollers before and after sugar beet sowing investigations. According to the results of experiments, reduction of primary soil tillage conserved soil water. The highest storage of soil water in spring was observed in non-reversibly tilled or not tilled soil. Subsoiling led higher water infiltration rate, and top layer of subsoiled soil consisted less moisture content than ploughed. Sugar beet seedbed moisture mostly depended on soil tillage intensity and depth. Presowing rotary tilling was the top tillage method in the case of water preservation in ploughed or unploughed soil. Soil compressing with rollers mostly had negative or low influence on light loam Luvisol moisture content. Rolling with Cambridge roller effected on more rapid water transport from deeper to top sugar beet seedbed layers and higher evaporation rate.
基金Agricultural Research Service,Grant/Award Number:5090-21000-065-00D。
文摘Background:Meadow fescue(Schedonorus pratensis(Huds.)P.Beauv.)is a reemerging pasture grass for temperate regions of North America.One disadvantage of this species is its lack of tolerance to frequent defoliation at low residual sward heights.This experiment was designed to conduct one cycle of selection and evaluation for persistence under frequent defoliation.Methods:The experiment included four locations with intensive grazing:two on silt loam soils and two on loamy sand soils.A fifth location was managed with frequent mowing to a 5-cm residual sward height,approximately 12-15 mowings per year.One cycle of selection was conducted with a population size of 1000 plants and 20 plants were selected for survivorship and vigor.Seed of all selected populations was evaluated at all five selection locations.Results:Gains were made in all eight populations,both due to increases in endophyte infection frequency and genetic gains associated with improved host genotypes.Selection was successful on both silt loam and loamy sand soils,but none of those gains were realized on the alternate soil type.Selection was successful at two of the four grazing farms,the two located on silt loam soils,but these gains were not realized on the farms with loamy sand soils or under the frequent mowing method of defoliation.Conclusions:Selection for tolerance to intensive grazing should be conducted under grazing conditions and selection for adaptation to both sandy and silt loam soils will require a more complex and imaginative selection scheme.
文摘Nutrients in agricultural runoff may cause offsite environmental impacts.The objective of this investigation was to examine nutrient transport by overland sheet flow on sites containing swine slurry.Data examined in this study was collected during field rainfall simulation tests conducted on cropland sites in southeast Nebraska,USA.Inflow was added to the top of experimental plots in four successive increments to simulate runoff rates occurring at greater downslope distances.Runoff rates on the experimental sites ranged from 2.3 to 21.2 L min^(-1) and maximum equivalent downslope distances varied from 5 to 108 m.Phosphorus(P)and nitrogen(N)transport rates were found to increase in a linear fashion with runoff rate.Hypothesis testing using the student’s t-test affirmed the prediction that a linear equation,calibrated for site specific conditions,can be used to relate nutrient transport rates to runoff rates.P and N transport rates were thought to be influenced by(a)the quantity of nutrients released by swine slurry at a particular runoff rate and(b)the amount of overland sheet flow available to transport the released nutrients.If nutrient transport rates can be linked to runoff rates,it may be possible to extrapolate experimental results obtained from small plots to greater downslope distances.Existing process-based models used to route overland sheet flow along hillslopes on upland areas could also be modified to include nutrient constituents.
文摘Background:Three water balance models were used to quantify water use efficiency on 71 golf courses in the United States.The golf courses were separated into five geographic regions.Methods:The United States Golf Association(USGA),Tipping-Bucket(TB),and Agro-IBIS(AG)water balance models were used to estimate golf course water requirements.Actual water use was divided by the water requirement from each model to generate three water efficiency scores for each golf course(WESUSGA,WESTB,and WESAG).Results:The mean WESUSGA was 1.16,the mean WESTB was 1.25,and the mean WESAG was 1.17.Thus,golf courses in this study used between 16%and 25%more water than predicted by the three models.The coefficients of variation of WESUSGA,WESTB,and WESAG were all 0.45 or higher,indicating that some golf courses used significantly more or less water than predicted by the models.Rooting depth,irrigated area,and soil texture were especially important modeling parameters for the golf course water requirement calculations.Conclusions:While onsite evaluation should still be carried out to verify the assumptions made by the water balance models,the models are promising tools to quickly identify golf course superintendents who are likely to be using water efficiently and those who could use less.
