During 1991~1995, the growth responses of young slash pine to N, P and K fertilizers and rational rate and ratio of fertilizers in yellow-red soil at Fengshushan Forest Farm, Jiangxi Province were studied. N fertilize...During 1991~1995, the growth responses of young slash pine to N, P and K fertilizers and rational rate and ratio of fertilizers in yellow-red soil at Fengshushan Forest Farm, Jiangxi Province were studied. N fertilizer decreased the growth of slash pine, while P not only significantly improved the increment of bottom diameter, height and crown diameter, but also caused earlier canopy closure of the stand. It also had a sustainable effect in the next two years. Slash pine had the most significant response to the treatment of 200 kg P2O5 ha-1, in which tree height, bottom diameter and crown diameter (EW and SN) were increased by 22%, 35%, 20% and 18% in 1994, 21%, 25%, 10% and 10% in 1995, respectively, compared to the control.Although there was no remarkable response to K fertilizer, good growth response to the application of 100 kg P2O5 plus 100 kg K2O ha-1 existed and tree height, bottom diameter and crown diameter (EW and SN)were increased by 31%, 14%, 23% and 21%, respectively, in 1993, compared to the control.展开更多
[Objectives] This study was conducted to explore the effects of different N application rates and densities on the growth and development of direct-seeding rape as well as on its yield.[Methods] A field experiment was...[Objectives] This study was conducted to explore the effects of different N application rates and densities on the growth and development of direct-seeding rape as well as on its yield.[Methods] A field experiment was carried out by setting five N fertilizer treatments and three density levels.[Results] Increasing seeding density and N application rate could improve the seed yield of rape. The suitable N application rate for the three densities were calculated using the fitted fertilizer efficiency models, respectively, to be 186.77, 221.35 and 236.14 kg/hm^2, at which the yields were the highest. The results showed that in this area, the seeding density of direct-seeding rape could be selected in the range of 6.0×10^5-7.5×10^5 plants/hm^2, and the suitable N application rate could be in the range of 221.35-236.14 kg/hm^2.[Conclusions] This study provides a theoretical basis for the maximization of spatial resource and efficient utilization of fertilizer.展开更多
Background： Forest fertilization offers a means to increase the production of renewable resources.Nitrogen is the most common fertilizer in boreal upland forests.There is plenty of research on the effect of nitrogen ...Background： Forest fertilization offers a means to increase the production of renewable resources.Nitrogen is the most common fertilizer in boreal upland forests.There is plenty of research on the effect of nitrogen fertilization on volume growth, but less research on the optimal timing of fertilization and optimal management of fertilized stands.Methods： This study used simulation and optimization to analyze the profitability of fertilization, optimal management of fertilized stands and the effects of fertilization on cash flows and timber yields.The management of 100 stands representing the most common growing sites of Scots pine and Norway spruce was optimized.Results： Fertilization improved profitability in most of the analyzed stands.Profitability improved most in spruce stands growing on mesic site.Improving stem quality increased the economic benefit of fertilization.The timber yields of medium-aged conifer stands can be increased by almost 1 m^3·ha^（-1）·a^（-1）（15%） in sub-xeric pine and mesic spruce sites and about 0.5 m^3·ha^（-1）·a^（-1）（5%） in mesic pine and herb-rich spruce sites when the recommended nitrogen dose（150kg·ha^（-1）） is applied once in 30 years.Conclusions： Nitrogen fertilization of boreal conifer forest should be used mainly in spruce-dominated stands growing on medium sites.The gains are the highest in stands where the mean tree diameter is 16–20 cm and stand basal area is 14–20 m^2·ha^（-1）.展开更多
文摘During 1991~1995, the growth responses of young slash pine to N, P and K fertilizers and rational rate and ratio of fertilizers in yellow-red soil at Fengshushan Forest Farm, Jiangxi Province were studied. N fertilizer decreased the growth of slash pine, while P not only significantly improved the increment of bottom diameter, height and crown diameter, but also caused earlier canopy closure of the stand. It also had a sustainable effect in the next two years. Slash pine had the most significant response to the treatment of 200 kg P2O5 ha-1, in which tree height, bottom diameter and crown diameter (EW and SN) were increased by 22%, 35%, 20% and 18% in 1994, 21%, 25%, 10% and 10% in 1995, respectively, compared to the control.Although there was no remarkable response to K fertilizer, good growth response to the application of 100 kg P2O5 plus 100 kg K2O ha-1 existed and tree height, bottom diameter and crown diameter (EW and SN)were increased by 31%, 14%, 23% and 21%, respectively, in 1993, compared to the control.
文摘[Objectives] This study was conducted to explore the effects of different N application rates and densities on the growth and development of direct-seeding rape as well as on its yield.[Methods] A field experiment was carried out by setting five N fertilizer treatments and three density levels.[Results] Increasing seeding density and N application rate could improve the seed yield of rape. The suitable N application rate for the three densities were calculated using the fitted fertilizer efficiency models, respectively, to be 186.77, 221.35 and 236.14 kg/hm^2, at which the yields were the highest. The results showed that in this area, the seeding density of direct-seeding rape could be selected in the range of 6.0×10^5-7.5×10^5 plants/hm^2, and the suitable N application rate could be in the range of 221.35-236.14 kg/hm^2.[Conclusions] This study provides a theoretical basis for the maximization of spatial resource and efficient utilization of fertilizer.
文摘Background： Forest fertilization offers a means to increase the production of renewable resources.Nitrogen is the most common fertilizer in boreal upland forests.There is plenty of research on the effect of nitrogen fertilization on volume growth, but less research on the optimal timing of fertilization and optimal management of fertilized stands.Methods： This study used simulation and optimization to analyze the profitability of fertilization, optimal management of fertilized stands and the effects of fertilization on cash flows and timber yields.The management of 100 stands representing the most common growing sites of Scots pine and Norway spruce was optimized.Results： Fertilization improved profitability in most of the analyzed stands.Profitability improved most in spruce stands growing on mesic site.Improving stem quality increased the economic benefit of fertilization.The timber yields of medium-aged conifer stands can be increased by almost 1 m^3·ha^（-1）·a^（-1）（15%） in sub-xeric pine and mesic spruce sites and about 0.5 m^3·ha^（-1）·a^（-1）（5%） in mesic pine and herb-rich spruce sites when the recommended nitrogen dose（150kg·ha^（-1）） is applied once in 30 years.Conclusions： Nitrogen fertilization of boreal conifer forest should be used mainly in spruce-dominated stands growing on medium sites.The gains are the highest in stands where the mean tree diameter is 16–20 cm and stand basal area is 14–20 m^2·ha^（-1）.
