Yield And Utilization Of Water And Nitrogen For Winter Wheat/Summer Maize Affected By Nitrogen And Phosphorus On Dry-Land

Nitrogen(N) and phosphorus(P) are essential nutrients for crop,and play an important role in increasing yield and quality of dry-land crops.However,unreasonable fertilizer inputs of nitrogen and phosphorus result in crop quality decline,waste of resources and environment deterioration,restricting the efficient and sustainable development of agriculture.A long-term field experiment were carried out in a rotation system of winter wheat and summer maize at different N and P rates to study the effects of N and P fertilization on accumulation of dry matter,grain yield and the utilization of nutrients.The main conclusion as follows:The winter wheat tillers elevated at elongation stage and the above ground biomass and grain yield increased at harvesting with the increase of N rates,but the harvest index increased unobviously.N application increased water accumulation,but decreased the yield formation efficiency of unit water mass.The accumulation speed and mass of plant water and dry matter increased with the increased N rates.At harvesting,the mass of water loss increased with the increased of N rates and water accumulation decreased significantly by 31.52 T/ha with applying 320kg N /ha.The decrease of dry matter accumulated in aboveground plant parts,spike and grain were different with N fertilization rates.When application of N,the accumulation of N,P and K and their maximum accumulation rates in winter wheat were increased,compared to no N fertilization.The maximum N accumulation rates occurred earlier with the increased of N rates.When applied 80,160,240 and 320kg N /ha,the maximum N accumulation rates were 40,43,57 and 85 days earlier than that of 0 kg N/ha treatment,respectively.The yield formation efficiency of maximum N uptake decreased,that of maximum P uptake elevated,while that of P uptake production efficiency had no significant changes compared to 0 kg N/ha treatment.The loss of K from aboveground plants of winter wheat at the late growth stages increased significantly when N applied.Whether applying P or not,the aboveground biomass and grain yield increased un-obviously at harvesting.P application could increased tillers at elongation stage and accumulation of water in aboveground plant.Yield formation efficiency of unit water decreased with the increase of P₂O₅ rates.At harvesting,the mass of water loss inreased with the increase of P rates,but water accumulation decreased significantly by 28.77 T/ha with applying 150kg P₂O₅ /ha.The decrease of dry matter from aboveground biomass,spike and grain were also decreased significantly when P fertilization applied.4.When application of P,the N,P and K accumulation and their maximum rates in winter wheat and their maximum yield formation efficiency decreased,compared to no P fertilization.The loss of N,P and K from winter wheat increased significantly with the increased of P rates at the late growth stages.5.After winter wheat harvesting,the water content in 60-300cm layers decreased significantly and showed a obvious trend to moving upward to top soil with the increase of cropping years and N rates.Soil nitrate and ammonium contents in the subsoil when N supply were deficiency.Nitrate and ammonium contents were increased by excessive N application, and showed a trend to be leached to subsoil layers in every year.The peak value of soil water content and its accumulation decreased and their change range increased with the increase of cropping years and P rates.There was no effect of P rates on soil ammonium content determined winter wheat harvest.6.With the increase of N rates before winter wheat seeding,summer maize grain yield increased,However,its biomass decreased with the increase of cropping years.P fertilization application before winter wheat seeding don't affected summer maize yield.The N,P and K accumulation of summer maize increased with the increased of N rates,but the N and K accumulation decreased and P accumulation was not affected with the increase of P rates.Soil water contents below 60cm soil layer decreased significantly with the increased of N rates after summer maize harvest,and P rates had no effect on soil water content.The accumulation of nitrate in soil profiles increased and leached to subsoil layers with the increase of cropping years when N fertilizer was applied.However,P application showed no effect on it.Whether applying N or P fertilizer,the soil ammonium was not affected,but it had the decreased trend in generally.