Effects of controlled alternate partial rootzone irrigation on soil microorganism and growth of maize

Chinese. 研究不同的灌溉方法和灌水量对根区土壤微生物及作物生长的影响。利用盆栽试验对供试玉米采取3种灌水方式，即常规全部根系区域灌水（常规）、固定1/2根系区域灌水（固定）和交替1/2根系区域灌水（交替）。每种灌水方式设３种供水水平：充分灌水（充分）、轻度水分亏缺（轻度）、重度水分亏缺（重度）。测定土壤微生物数量、作物株高、茎粗及叶面积，记录每次灌水量。在同一灌水方式下，轻度的水分亏缺处理下土壤微生物数量占有一定的优势，有时甚至高于充分灌水处理。交替1/2根系灌水根系两侧土壤微生物数量分布均匀。作物充分灌水时，生长最旺盛，轻度亏缺次之，重度最次。轻度的水分亏缺能有效地改善土壤的水分、通气等条件，从而有利于土壤微生物的繁殖。在不同灌水方式下，由于交替1/2根系灌水使根系区土壤处于交替干燥和湿润，在提供生命活动所需水分的同时，使土壤孔隙处于良好的通气条件下，为土壤微生物提供了有益的生存条件，因此显示出其明显的优越性。充分灌水处理中，常规方式灌水所得干物质量达到最大。交替灌充分灌水处理耗水与常规灌重度水分亏缺相近，但其干物质量却相对常规灌增加了50％。交替灌的水分利用效率达到最优。

English. The effects of soil microorganisms and growth of crop were investigated in a pot experiment of maize. The irrigation treatments included: a. conventional irrigation, b. fixed partial rootzone irrigation, c. alternate partial rootzone irrigation.For each irrigation method, water was supplied by three levels: sufficient irrigation, milder deficiency irrigation, serious deficiency irrigation. The quantity of soil microorganism, plant height, stalk diameter, leaf area, dry biomass and irrigation amount were measured. Under a milder deficiency irrigation level, plant soil microorganisms were not significantly inhibited, and their growth quantity was at times larger than sufficient irrigated treatment. The soil microorganisms distributed evenly under alternate partial rootzone irrigation. The plant grew very well under sufficient irrigation. The milder deficiency irrigation was slightly worse, but not significantly so. This suggests that the condition of soil water content and ventilation were ameliorated in the milder deficiency irrigation level. Soil microorganisms multiplied. Under alternate partial root zone irrigation, where soil was kept in alternately dry and moist conditions, soil was in a nicer ventilate state, which provided a beneficial condition for the soil microorganisms. Superiority of alternative irrigation was displayed in different irrigation ways. The largest dry biomass was obtained under conventional irrigation. Under sufficient alternate irrigation and severely deficit conventional irrigation, conditions were the same, but the dry biomass under the former was increased by 50%, compared to the latter. The best water use efficiency was obtained under alternate irrigation.