灌溉施肥水平对盐渍化农田水盐分布及玉米产量的影响

水资源缺乏和过量施肥影响着干旱半干旱盐渍化地区农业的发展.研究不同灌溉和施肥量对土壤水盐分布和青贮玉米产量的影响,可为该区确定适宜的灌溉和施肥量提供依据.试验于2015和2016年在大同盆地的盐渍化农田进行,设3种灌溉水平:土壤水分上限分别为田间持水率(θ_f)的100%(W₁)、90%(W₂)和80%(W₃),根据各处理灌溉前的土壤平均实际含水率计算灌水量;2015年设4种施肥水平:900(F₁)、750(F₂)、600(F₃)和450 kg·hm^-2(F₄),2016年设F₁、F₂和F₃共3种.试验用化肥为缓释复合肥,总养分含量48%,其中N:P₂O₅:K₂O的比例为30:12:6.结果表明: 土壤表层电导率随施肥量的增加而增大,施肥水平对平均电导率(EC)和含水率的影响在0～10 cm土层显著,与F₁相比,F₂的0～10 cm土层平均EC在2015年和2016年分别降低25.6%～42.7%和6.4%～7.7%.20～80 cm土层的水分含量随施肥量的增加而降低,与F₁相比,2015年F₂、F₃和F₄处理20～80 cm土层平均土壤含水率分别增加5.9%、16.7%和16.7%,2016年F₂和F₃分别增加13.3%和16.7%.产量在两年中均表现为F₁和F₂高于F₃和F₄,W₃低于W₁和W₂; F₁和F₂的产量差异不明显;与W₁相比,W₂的产量减少低于15 %.因此,施复合肥600～750 kg·hm^-2(氮肥含量180～270 kg·hm^-2),且灌溉水平为W₁和W₂时,可以保证该地区盐渍化土壤种植玉米获得较高的产量,并且不会造成根系层的盐分积累.

Effects of irrigation and fertilizer levels on the distribution of water and salt in saline field and maize yield

Agriculture development in arid and semi-arid saline areas is seriously affected by water resources scarcity and excessive fertilization. Understanding the effects of different irrigation and fertilization levels on soil water and salt distribution and silage maize yield would provide scientific basis for determining appropriate irrigation and fertilization amount. The experiment was carried out in a saline field of the Datong Basin in 2015 and 2016. There were three irrigation levels, with the upper limit of soil moisture being controlled at 100% (W₁), 90% (W₂) and 80% (W₃) of the field water capacity. Irrigation amount was calculated based on the average actual water content before irrigation of each treatment. There were four fertilization levels in 2015, 900 kg·hm^-2 (F₁), 750 kg·hm^-2 (F₂), 600 kg·hm^-2(F₃), and 450 kg·hm^-2(F₄), and three levels in 2016 (F₁, F₂, and F₃). The total nutrient content of the slow-release compound fertilizer was 48%, with a 30:12:6 ratio of N:P₂O₅:K₂O. Results showed that the surface conductivity of soil increased with the increases of fertilizer application levels. The effects of fertilization on soil salinity in 0-10 cm was significant. Compared with F₁, the average EC of F₂ in 0-10 cm was decreased by 25.6%-42.7% in 2015 and by 6.4%-7.7% in 2016, respectively. The water content in 20-80 cm decreased with the increases of fertilizer application levels. Compared with F₁, the average soil water content in 20-80 cm soil layer of F₂, F₃, and F₄ increased by 5.9%, 16.7% and 16.7% in 2015, and that of F₂ and F₃ increased by 13.3% and 16.7% in 2016, respectively. The yield of F₁ and F₂ was higher than that of F₃ and F₄, and W₃ was lower than W₁ and W₂ in both years. There was no significant difference in yield between F₁ and F₂. Compared with W₁, decrease in yield of W₂ was less than 15%. Therefore, the application of compound fertilizer 600-750 kg·hm^-2(nitrogen content 180-270 kg·hm^-2), and irrigation levels W₁ and W₂ were suggested to ensure high yield of forage maize in saline soil in this area, without salt accumulation in root zone.