Effects Of Nitrogen Fertilizer Regulation And Soil Surface Mulching On Yield And Water And Nitrogen Use By Winter Wheat On Dryland

Less precipitation and its uneven distribution across seasons, over fertilizationand unreasonable fertilization, and lack of effective water harvesting cultivations areconsidered as major problems long-termly facing the dryland agriculture in northwestChina. Long term field experiments were carried out to work on fertilization andcultivation management for increasing crop yield, to study the effects of topdressingat early spring(TS), N fertilizer regulation and topdressing at early spring(NF+TS), Nfertilizer regulation and ridge mulching with furrow seeding(NF+RM) and N fertilizerregulation and ridge mulching with furrow seeding at high seedingdensity(NF+RM+HS) on yield, water use efficiency, utilization efficiency of nutrientof winter wheat. The results showed:1. The effects of TS on winter wheat yield were different with years. The grainyield was obviously increased by22.2%,38.6%and24.8%, respectively for thetreatments of NF+TS, NF+RM and NF+RM+HS in the first cropping years, andcorrespondingly by5.9%,7.6%and12.7%in the second cropping years.Spikenumber per hectare was main factor in winter wheat yield components.2. Water use efficiency was obviously increased by20.9%,26.4%and11.8%respectively for the treatments of NF+TS, NF+RM and NF+RM+HS in the firstcropping years, and correspondingly by9.8%,11.5%and12.3%in the secondcropping years. N partial factor productivity was increased by32.0%,49.6%and34.8%in the first year, correspondingly by17.5%,13.5%and19.0%in the secondyear. N physiological efficiency was increased by11.4%,35.1%and61.8%in thefirst year, correspondingly by6.1%,25.7%and24.9%in the second year.3. TS, NF+TS, NF+RM and NF+RM+HS could decrease residual nitrate-N incurrent season and residues of nitrate N in0-300cm soil and leaching amount.4. Plastic film mulching combined with straw mulching could increase soil waterstorage before sowing during summer fallow of winter wheat. Compared with nomulching, plastic film mulching increased soil water storage before sowing by13,18 and21mm on the average of four years. Soil water storage before sowing showed asignificant linear correlation with yield.5. Plastic film mulching increased water storage in0~100cm soil layers atflowering stage by8.4%and13.3%for NF+RM and NF+RM+HS in the firstcropping years, and7.0%,7.9%in the second year, but soil residual nitrate Ndecreased by47.0%,52.9%in the first cropping years, by28.7%,28.9%in the secondyear.6. Plastic film mulching could decrease grain nitrogen content, by14.0%forNF+RM+HS, and correspondingly by16.5%and17.0%for NF+RM andNF+RM+HS in the second cropping years.For the purpose of simultaneously increasing water and nutrient efficiency andyield, NF+RM was proved to be an effective cultivation pattern on dryland, while Nfertilizer rates for topdressing should be properly increased in order to elevate the soilnitrate N at flowering and grain nitrogen contents...