| Magnesium(Mg)is an essential nutrient element for the growth and development of crops and the lack of magnesium will seriously affect the yield and quality of vegetables.In recent years,soil magnesium leaching losses have been severe,due to regional characteristics such as high temperature and rain in the southwest region and high soil acidification.With the irrational input of nitrogen,phosphorus,and potassium fertilizers and the lack of application of magnesium fertilizer,magnesium has gradually become the limit factor of crop yield and quality in the southwest China.Furthermore,the low-yield and inefficient crop systems bring big environmental cost.Magnesium fertilizer application has become an important measure to improve crop yield and quality and reduce environmental effects.At present,the fast-acting magnesium fertilizers have higher biological effectiveness,but they are easily lost from the soil by leaching and runoff due to their higher water solubility.Although the slow-acting magnesium fertilizer is not easy to be lost from the soil,it is difficult to match the growth demand of crops in a short time due to its low biological effectiveness.Therefore,it is urgent to develop and apply new magnesium fertilizers to prevent and control leaching,in order to improve fertilizer utilization efficiency,and reduce environmental costs.To this end,in this study,on the one hand,we designed a calcium and magnesium-containing pepper and cabbage formula fertilizer,which based on the growth demand and optimization the proportion of nitrogen,phosphorus,potassium,calcium,and magnesium in pepper and cabbage in Southwest China.Furthermore,their effects on the growth and development of pepper and cabbage and their environmental effects were evaluated in field experiments.On the other hand,magnesium fertilizers(nano-magnesium hydroxide(NMH),modified nanomagnesium hydroxide(M-NMH),and magnesium ammonium phosphate(MAP)),were compared with traditional magnesium sulfate fertilizers(MS)in field experiments.The effects of different new magnesium fertilizers on the growth and development in typical pepper-cabbage vegetable rotation systems in Southwest China were recorded and their environmental effects were monitored.The leaching losses and biological effectiveness of different new magnesium fertilizers were quantified in pot experiments.It is expected to provide theoretical basis and technical support for the magnesium nutrition management of pepper-cabbage high-yield,high-efficiency cultivation system.The results of field experiment with the calcium-magnesium-containing formula fertilizer show that: the calcium-magnesium pepper-cabbage formula fertilizer has a significant positive effect in the southwestern pepper-cabbage planting system,which can better match the development demand of pepper-cabbage production.While improving the partial productivity of nitrogen and phosphorus fertilizers,it can greatly reduce the loss of active nitrogen in agricultural production.Greenhouse gas emission potential,acidification effect potential,eutrophication effect potential,reducing environmental costs.(1)In the two-year' pepper experiment in two experimental stations,the application of calcium-magnesium-containing ordinary compound fertilizer and calciummagnesium-containing pepper formula fertilizer significantly increased the dry matter accumulation and yield of pepper,increasing the yield by 30.6~44.3%,increasing nitrogen fertilizer partial productivity by 30.5~37.3%,increased soil calcium and magnesium surplus,and significantly improved farmers' economic benefits.In addition,in the experiment in 2018,the application of calcium-magnesium-containing common compound fertilizer and calcium-magnesium-containing pepper formula fertilizer promoted the transfer of potassium,calcium,and magnesium nutrients of pepper plants to the edible part,increasing fruit Vc content.(2)In the cabbage experiment,the treatment of calcium-magnesium-containing ordinary compound fertilizer and calciummagnesium-containing formula fertilizer significantly increased the dry matter accumulation and yield of cabbage,increasing the yield by 12.8~19.3%,and increasing the partial nitrogen productivity by 6.67~12.8%,The soil calcium and magnesium surplus increased,and increase the Vc content of cabbage.(3)Compared with farmers' fertilization,reduced fertilization,formula fertilizer treatment and calcium-magnesium formula fertilizer treatment can significantly reduce the loss of active nitrogen,the potential value of greenhouse gas emissions,the potential value of acidification effect,and the potential value of eutrophication effect.The results of the new magnesium fertilizer in field experiment showed that:(1)The application of magnesium sulfate can improve the yield of pepper cabbage,but the effect of several new magnesium fertilizers is better.Compared with control(CK),the application of MS?NMH?M-NMH and MAP increased pepper yield by 13.2%,31.6%,23.1% and 22.2%(Two-year average),cabbage yield by 6.24%,17.2%,19.2% and 1.41%,respectively.(2)The application of new magnesium fertilizer can improve the absorption and accumulation of potassium and magnesium in pepper-cabbage,and the effect is better than magnesium sulfate.In addition,the application of magnesium fertilizer has a tendency to increase the Vc content in pepper-cabbage,the new magnesium fertilizer treatment has a slightly higher Vc content than the magnesium sulfate treatment.(3)The new magnesium fertilizer can improve the utilization efficiency of magnesium fertilizer and partial productivity of nitrogen and phosphorus fertilizer,reduce the environmental load of farmland and reduce the environmental cost.On pepper,the utilization rate and agronomic efficiency of each magnesium fertilizer are: MAP> NMH> M-NMH> MS.On cabbage,the utilization rate and agronomic efficiency of each magnesium fertilizer are: M-NMH> NMH> MS> MAP.The results of potted leaching experiment showed:(1)Compared with the application of MS,the application of M-NMH and NMH can significantly improve the physiological indexes of pepper plant height,stem thickness and relative chlorophyll content at various stages,and promote potassium,calcium,and magnesium accumulate,which improves the quality of dry matter above the ground and the yield of pepper.The application of medium amount of M-NMH in cabbage and application of high amount of NMH also have a positive effect of increasing yield.In addition,the effect of MAP on pepper is also relatively significant,with a relative increase in yield of 41.6%,but basically no significant effect on the growth of cabbage;Polyhalite(Poly)has a relatively good effect on cabbage,a relatively increased yield of 9.98%,but no effect on the growth of pepper significantly affected.(2)The application of M-NMH,NMH and MAP on peppers can reduce the leaching losses of potassium,calcium and magnesium relative to the application of MS.On pepper,the order of magnesium leaching rate is: Poly> MS> NMH > M-NMH>MAP.On cabbage,the order of magnesium leaching rate(average of the two magnesium supply levels)is: Poly>MAP> M-NMH> MS> NMH.In summary,calcium-magnesium-containing peppers and cabbage formula fertilizers can better match the nutrient requirements of the pepper-cabbage system in southwestern China,increase vegetable yields and fertilizer utilization rates while reducing environmental costs.Compared with MS,NMH,M-NMH and MAP can more effectively control the leaching loss,better match the needs of pepper-cabbage growth and development. |
PDF Full Text Request