Tissue culture (TC) banana plantlets at the in vitro stage are delicate and devoid of microbes and nutrients that are essential for establishment and subsequent growth. Some microbes are known for function best under ...Tissue culture (TC) banana plantlets at the in vitro stage are delicate and devoid of microbes and nutrients that are essential for establishment and subsequent growth. Some microbes are known for function best under certain soil threshold levels of macro and micronutrients and have been associated with growth and performance of TC banana. A green house and field study was conducted to evaluate the effect of combining two commercial biological products [Rhizatech and ECO-T (mycorrhiza and Trichoderma based products, respectively)] with various sources of nitrogen and phosphorous including Mavuno, Minjingu phosphate rock, Calcium Ammonium Nitrate (CAN), manure and diammonium phosphate (DAP) on growth and performance of TC banana in Vertisol and Rhodic Ferralsol soil conditions. Tissue culture plants were initially inoculated with Rhizatech and ECO-T at the acclimatization stage and subsequently at the beginning of the potting stage and field establishment. Addition of nutrient sources was also done at the same stages of plant growth by mixing with the soil substrates prior to planting. The performance of plants was significantly (at p ≤ 0.05) affected by the combinations of nutrient sources depending on the soil type and stage of plant development. The growth of plants in the Vertisol increased with Trichoderma combined with either organic manure, DAP or combined with a macro and micro nutrient source (Mavuno) as compared to the sole application of Trichoderma. Performance of plants treated with combination of mycorrhiza and either Mavuno and minjigu rock phosphate was consistently higher in the Rhodic Ferralsol than either mycorrhiza alone or fertilizer alone. This indicates that TC plants could highly benefit from combined application of microbiological products and inorganic and organic fertilizers. However, a prior knowledge of the product’s microbial formulation and prevailing soil conditions is essential for optimizing the potential benefits of integrating microbe-based product with inorganic and organic fertilizers.展开更多
The knowledge that soil microorganisms form an important component of below ground biodiversity, providing ecosystem services, is often not incorporated in formulation of policies to conserve and manage these microorg...The knowledge that soil microorganisms form an important component of below ground biodiversity, providing ecosystem services, is often not incorporated in formulation of policies to conserve and manage these microorganisms. Using the method of cost replacement or cost savings in terms of mineral nitrogen fertilizer that would have been required to attain the same level of nitrogen fixed biologically, this study contributes to awareness on the importance of these microorganisms. Applying the knowledge gained from several on-station and on-farm trials in Africa, complemented with assumptions on FAO-sourced data from 19 African countries, this study estimated the financial value of nitrogen fixation of legume nodulating bacteria （LNB） associated with promiscuous soybean varieties. Results show that the financial value of the nitrogen-fixing attribute of soybean in Africa, especially the promiscuous varieties, annually amounts to about $ 200 million US dollars across the 19 countries. With the fertilizer price of -$ 795 tl （June 2008）, this would amount to $ 375 million. The study recommends various ways of increasing the chances of smallholder farmers benefiting from the nitrogen-fixing attribute of LNB, especially since many cannot afford adequate quantities of inorganic fertilizers for increased crop productivity.展开更多
Wise decision-making on resource allocation and intervention targeting for soil management cannot rely solely on trial and error methods and field observations used by small-scale farmers： cost-effective soil fertili...Wise decision-making on resource allocation and intervention targeting for soil management cannot rely solely on trial and error methods and field observations used by small-scale farmers： cost-effective soil fertility survey methods are needed. This study aimed to test the applicability of infrared spectroscopy （IR） as a diagnostic screening tool for making soil fertility recommendations in small-scale production systems. Soil fertility survey of 150 small-scale groundnut farms in western Kenya was conducted using a spatially stratified random sampling strategy. Soil properties examined were pH in water （pHw）, total carbon （C）, total nitrogen （N）, extractable phosphorus （P）, exchangeable potassium （K）, calcium （Ca）, magnesium （Mg） and texture. These properties were calibrated to mid-infrared （MIR） diffuse reflectance using partial least square regression （PLSR）. Cross-validated coefficient of determination （r2） values obtained from calibration models were 〉 0.80 for all properties, except P and K with 0.66 and 0.50 respectively. Soil nutritional deficiencies were evaluated using critical nutrient limits based on IR predictions and composite soil fertility indices （SFIs） developed from the soil properties using principal component analysis. The SFIs were calibrated to MIR soil spectral reflectance with cross-validated r： values 〉 0.80. The survey showed that 56% of the groundnut farms had severe soil nutrient constraints for production, especially exchangeable Ca, available P and organic matter. IR can provide a robust tool for farm soil fertility assessment and recommendation systems when backed up by conventional reference analyses. However, further work is required to test direct calibration of crop responses to spectral indicators and to improve prediction of extractable P and K tests.展开更多
文摘Tissue culture (TC) banana plantlets at the in vitro stage are delicate and devoid of microbes and nutrients that are essential for establishment and subsequent growth. Some microbes are known for function best under certain soil threshold levels of macro and micronutrients and have been associated with growth and performance of TC banana. A green house and field study was conducted to evaluate the effect of combining two commercial biological products [Rhizatech and ECO-T (mycorrhiza and Trichoderma based products, respectively)] with various sources of nitrogen and phosphorous including Mavuno, Minjingu phosphate rock, Calcium Ammonium Nitrate (CAN), manure and diammonium phosphate (DAP) on growth and performance of TC banana in Vertisol and Rhodic Ferralsol soil conditions. Tissue culture plants were initially inoculated with Rhizatech and ECO-T at the acclimatization stage and subsequently at the beginning of the potting stage and field establishment. Addition of nutrient sources was also done at the same stages of plant growth by mixing with the soil substrates prior to planting. The performance of plants was significantly (at p ≤ 0.05) affected by the combinations of nutrient sources depending on the soil type and stage of plant development. The growth of plants in the Vertisol increased with Trichoderma combined with either organic manure, DAP or combined with a macro and micro nutrient source (Mavuno) as compared to the sole application of Trichoderma. Performance of plants treated with combination of mycorrhiza and either Mavuno and minjigu rock phosphate was consistently higher in the Rhodic Ferralsol than either mycorrhiza alone or fertilizer alone. This indicates that TC plants could highly benefit from combined application of microbiological products and inorganic and organic fertilizers. However, a prior knowledge of the product’s microbial formulation and prevailing soil conditions is essential for optimizing the potential benefits of integrating microbe-based product with inorganic and organic fertilizers.
文摘The knowledge that soil microorganisms form an important component of below ground biodiversity, providing ecosystem services, is often not incorporated in formulation of policies to conserve and manage these microorganisms. Using the method of cost replacement or cost savings in terms of mineral nitrogen fertilizer that would have been required to attain the same level of nitrogen fixed biologically, this study contributes to awareness on the importance of these microorganisms. Applying the knowledge gained from several on-station and on-farm trials in Africa, complemented with assumptions on FAO-sourced data from 19 African countries, this study estimated the financial value of nitrogen fixation of legume nodulating bacteria （LNB） associated with promiscuous soybean varieties. Results show that the financial value of the nitrogen-fixing attribute of soybean in Africa, especially the promiscuous varieties, annually amounts to about $ 200 million US dollars across the 19 countries. With the fertilizer price of -$ 795 tl （June 2008）, this would amount to $ 375 million. The study recommends various ways of increasing the chances of smallholder farmers benefiting from the nitrogen-fixing attribute of LNB, especially since many cannot afford adequate quantities of inorganic fertilizers for increased crop productivity.
文摘Wise decision-making on resource allocation and intervention targeting for soil management cannot rely solely on trial and error methods and field observations used by small-scale farmers： cost-effective soil fertility survey methods are needed. This study aimed to test the applicability of infrared spectroscopy （IR） as a diagnostic screening tool for making soil fertility recommendations in small-scale production systems. Soil fertility survey of 150 small-scale groundnut farms in western Kenya was conducted using a spatially stratified random sampling strategy. Soil properties examined were pH in water （pHw）, total carbon （C）, total nitrogen （N）, extractable phosphorus （P）, exchangeable potassium （K）, calcium （Ca）, magnesium （Mg） and texture. These properties were calibrated to mid-infrared （MIR） diffuse reflectance using partial least square regression （PLSR）. Cross-validated coefficient of determination （r2） values obtained from calibration models were 〉 0.80 for all properties, except P and K with 0.66 and 0.50 respectively. Soil nutritional deficiencies were evaluated using critical nutrient limits based on IR predictions and composite soil fertility indices （SFIs） developed from the soil properties using principal component analysis. The SFIs were calibrated to MIR soil spectral reflectance with cross-validated r： values 〉 0.80. The survey showed that 56% of the groundnut farms had severe soil nutrient constraints for production, especially exchangeable Ca, available P and organic matter. IR can provide a robust tool for farm soil fertility assessment and recommendation systems when backed up by conventional reference analyses. However, further work is required to test direct calibration of crop responses to spectral indicators and to improve prediction of extractable P and K tests.
