[Regulation effects of irrigation methods and nitrogen application on soil water, nitrate, and wheat growth and development].

Field experiments were conducted to examine the effects of flooding irrigation (FI), micro-sprinkler irrigation (SI), drip irrigation (DI), combined with nitrogen application (N1:157.5 kg·hm-2 as basal, 67.5 kg·hm-2 top dressed at jointing stage; N2:157.5 kg·hm-2 as ba-sal, 45 kg·hm-2 and 22.5 kg·hm-2 top dressed at jointing stage and filling stage, respectively) on soil moisture, nitrate (NO3--N) content, and wheat growth and development, under maize straw returning to field. Results showed that irrigation methods and nitrogen application modes affected soil water content and soil water storage (SWS). Irrigation methods had limited effect on soil water content in the 0-60 cm soil depth at the wintering and re-greening stages, 0-160 cm soil depth at the booting and filling stages, 100-160 cm soil depth at the mature stage, but had substantial effect on water content in the 80-160 cm soil depth at the wintering and re-greening stages, 0-80 cm soil depth at the mature stage. The effects of irrigation methods on water content and SWS were in the order of FI>DI>SI. Under SI and DI, water content, SWS of soil layers, and their changes increased with increasing irrigation rate. Nitrogen application had obvious effect on NO3--N content in the 0-20 cm soil depth. In the SI, variation of NO3--N content among different growth stages was evident. In the DI, changes of NO3--N content were non-evident during wintering and booting stages, and were evident after booting stage, with opposite change treand in the FI. In general, NO3--N content was influenced by irrigation rate at early and middle stages of wheat growth, but was mainly affected by N application at late stage. In the SI and DI, NO3--N content changed larger by irrigation rate before winter. Total stem number and tillers per plant during overwintering period, panicle number rate, panicle number, yield, WUE and nitrogen use efficiency (NUE) were in the order of SI>DI>FI. In the SI and DI, total stem number and panicle number were higher in the N1 than that in the N2, but grain number per panicle, 1000-grain mass, yield, WUE and NUE were lower. Sowing wheat after maize straw returning to the field, replacing FI with micro-sprinkler irrigation four times during the wheat growth period, applying sufficient basal fertilizer and then topdressing at jointing and filling stages, are the high-efficiency and water-saving cultivation strategies of wheat in wheat-maize double cropping area in southern Shanxi.为探明玉米秸秆还田下小麦的合理灌溉与施肥方法,于田间研究了漫灌(FI)、微喷灌(SI)、滴灌(DI)和灌水施氮模式(N1, 基施纯N 157.5 kg·hm-2+拔节期施纯N 67.5 kg·hm-2; N2, 基施纯N 157.5 kg·hm-2+拔节期施纯N 45.0 kg·hm-2+灌浆期施N 22.5 kg·hm-2)对土壤水分、硝态氮(NO3--N)含量和小麦生长发育的影响.结果表明: 灌溉方法和灌水施氮模式共同影响土壤含水量和贮水量的变化.其中,灌溉方法对越冬期和返青期0～60 cm、孕穗期和灌浆期0～160 cm、成熟期100～160 cm土层含水量影响相对较小,对越冬期和返青期80～160 cm、成熟期0～80 cm土层含水量影响大;FI对含水量和贮水量影响最大,DI次之,SI最小;SI和DI的灌水施氮模式中灌水量多,则土层含水量高、贮水量多,变化大.NO3--N含量受灌溉方法和施氮的影响,施氮对0～20 cm土层影响大,SI生育期NO3--N含量变化大,DI越冬期至孕穗期NO3--N含量变化小,此后变化大,FI与DI相反;生育前中期灌水量对NO3--N含量影响大,后期施氮对NO3--N含量影响大;SI和DI的2种灌水施氮模式中冬前灌水量多的NO3--N含量变化大.灌溉方法中SI越冬期总茎数和单株分蘖高,成穗率高,成穗数多,产量、水分利用效率(WUE)和氮素利用效率最高,滴灌次之,漫灌最低;SI和DI中N1生育期总茎数、成穗数多,但穗粒数和千粒重低,产量、WUE和氮素利用效率低于N2.因此,玉米秸秆还田后播种小麦,微喷灌代替漫灌生育期灌4水,施足基肥,拔节期和灌浆期分次追氮,是山西南部小麦-玉米一年两熟区小麦节水高产高效栽培模式.