| Soil erosion caused the reduction of cultivated land area in the hilly and gully region of the Loess Plateau,which also reduced land quality and declined land productivity.The severe shortage of water resources and poor irrigation conditions are the main factors that constrain the economic benefits of crops in the region.Straw mulching and no-tillage farming measures are the core soil and water conservation tillage techniques,which can improve the soil's storage fertility and bottom entropy ability.At the same time,it can also increase rainfall infiltration,thus achieving the purpose of preventing soil erosion.The experiment adopted four different farming measures?traditional tillage?T?,no-tillage?NT?,traditional tillage straw cover?TS?,no-till straw cover?NTS??to study the soil water and the vertical distribution of nitrogen in the soil during the growth period of different wheat.The nitrogen uptake and distribution of spring wheat plants can be analyzed to find the best combination of farming measures.This study aims to provide a scientific theoretical basis for the promotion of suitable conservation tillage measures in Gansu Province.The results show:?1?Compared with traditional tillage?T?treatment,no-tillage straw mulching?NTS?can increase the soil water content of 0-40 cm soil layer to varying degrees,increasing by15.1%-35.9%.The soil moisture content is the highest during the growth period of spring wheat.?2?Compared with traditional tillage?T?treatment,no-tillage straw mulching?NTS?can reduce the nitrate content of soil in 0-40 cm soil layer,with a decrease of 23.7%-80.8%.Under this treatment,the soil nitrate nitrogen is the lowest during the growth period of spring wheat.?3?NTS treatment can promote the accumulation of total nitrogen in soils in different soil layers,and the total nitrogen content of soil is mainly concentrated in the surface soil.Compared with the 0-10 cm,the average nitrogen content in the 10-20 cm and 20-40 cm decreased by 11.6%-18.2%and 29.0%-35.7%,respectively.The total nitrogen in the soil treated by NTS was the highest during the growth period of spring wheat.?4?Analysis of soil water and nitrogen in 0-40 cm soil layers of spring wheat under different tillage measures showed that soil moisture content of 0-40 cm soil layers in spring wheat was positively correlated with total nitrogen content and yield.However,soil water content was negatively correlated with nitrate nitrogen content,and soil nitrate nitrogen was also negatively correlated with total nitrogen and yield.?5?No-till straw mulching promoted the absorption and utilization of nitrogen by spring wheat.Compared with traditional tillage,no-tillage coverage has the function of preserving water storage and improving soil structure,which significantly improves nitrogen uptake during the booting-flowering period of wheat plants.Compared with traditional tillage?T?,the nitrogen uptake by TS,NT and NTS increased by 24.2%,3.9%and 58.7%,respectively,and the difference was significant?P<0.05?.?6?The distribution of nitrogen in the organs of spring wheat at maturity was satisfied:grain>stem+leaf sheath>leaf>root.Compared with traditional tillage,no-tillage significantly increased the nitrogen accumulation in the aboveground part and grain of spring wheat during the maturity of dryland.Under the condition of NTS treatment,the nitrogen distribution in the grain was the largest(152.78 kg·hm-2).Compared with NTS,T,TS,and NT treatments were reduced by 30.4%,12.1%,and 19.3%,respectively,and the difference between them was significant?P<0.05?.?7?NTS treatment can promote the transport and contribution rate of nitrogen to grain after anthesis.The amount of nitrogen transferred from the vegetative organs of spring wheat to the grain and the transfer rate were the highest after NTS treatment.NTS increased by 37.0%,8.2%,19.1%,and 22.4%,5.3%,and 9.5%,respectively.However,the contribution rate of nitrogen translocation to wheat by NTS was the smallest?73.04%?.?8?No-tillage straw mulching significantly promoted the nitrogen use efficiency of spring wheat.Compared with the nitrogen use efficiency under NTS treatment,T,TS and NT treatments decreased by 12.2%,5.3%and 8.7%,respectively,and the differences were significant?P<0.05?.The trends of nitrogen fertilizer production efficiency and harvest index were NTS>TS>NT>T,and NTS treatment was the highest,which was significantly higher than T treatment by 37.8%and 18.7%,respectively.The difference of treatment was significant?P<0.05?.Therefore,different tillage measures can regulate soil moisture and total nitrogen content to promote nitrate nitrogen uptake,thereby improving nitrogen uptake and utilization of spring wheat.Among them,no-tillage and straw mulching treatment can effectively regulate soil water movement and reduce nitrate accumulation,which is a high-efficiency tillage measure for improving soil water and fertilizer status and increasing crop yield on the Loess Plateau.In summary,no-tillage straw mulching treatment is the best tillage mode for soil water storage,fertilizer conservation and yield increase in this area. |
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