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

Abstract

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.