Jianliang Liu

Soil mulching can mitigate soil water deficiency impacts on rainfed maize production in semiarid environments

Temporally irregular rainfall distribution and inefficient rainwater management create severe constraints on crop production in rainfed semiarid areas. Gravel and plastic film mulching are effective methods for improving agricultural productivity and water utilization. However, the effects of these mulching practices on soil water supply and plant water use associated with crop yield are not well understood. A 3-yr study was conducted to analyze the occurrence and distribution of dry spells in a semiarid region of Northwest China and to evaluate the effects of non-mulching (CK), gravel mulching (GM) and plastic film mulching (FM) on the soil water supply, plant water use and maize (Zea mays L.) grain yield. Rainfall analysis showed that dry spells of ≥5 days occurred frequently in each of 3 yr, accounting for 59.9–69.2% of the maize growing periods. The >15-d dry spells during the jointing stage would expose maize plants to particularly severe water stress. Compared with the CK treatment, both the GM and FM treatments markedly increased soil water storage during the early growing season. In general, the total evapotranspiration (ET) was not significantly different among the three treatments, but the mulched treatments significantly increased the ratio of pre- to post-silking ET, which was closely associated with yield improvement. As a result, the grain yield significantly increased by 17.1, 70.3 and 16.7% for the GM treatment and by 28.3, 87.6 and 38.2% for the FM treatment in 2010, 2011 and 2012, respectively, compared with the CK treatment. Its concluded that both GM and FM are effective strategies for mitigating the impacts of water deficit and improving maize production in semiarid areas. However, FM is more effective than GM.

Nitrogen fertilization effects on nitrogen balance and use efficiency for film-mulched maize in a semiarid region

Efficient nitrogen (N) applications are crucial for sustainable agricultural development. A three-year field study was conducted to evaluate the effects of N fertilization on soil NO3-N contents, N balance, grain yield, and N use efficiency of film-mulched maize (Zea mays L.) in the semiarid northwest China. Six N levels were examined: 0 (N0), 100 (N100), 200 (N200), 250 (N250), 300 (N300), and 400 (N400) kg N ha−1. Results showed that residual soil NO3-N contents after harvest and apparent N losses markedly increased with increased N fertilizer rate. High accumulations of soil NO3-N were detected in the 80–200 cm layers in the N300 and N400 treatments in 2010 and 2011, indicating that excessive N applications resulted in NO3-N leaching in this semiarid region. The N use efficiency decreased with increased N fertilizer rate, but insignificant differences in agronomic efficiency, apparent recovery efficiency, and physiological efficiency were observed between N100, N200, and N250 treatments. Maize grain yields increased with N fertilization, but it did not further increase when N application was higher than plant N requirements. A linear plateau relationship was observed between grain yield and N supply (fertilizer N plus initial soil NO3-N in the 0–100 cm layers). The minimal N supply rate required to obtain the maximum yield (13.9 Mg ha−1) was 279 kg N ha−1, which was similar to plant N uptake and simultaneously reduced apparent N losses. We conclude that N fertilizer recommendations which consider soil NO3-N contents can simultaneously provide sufficient N for high yields and improve N fertilization of film-mulched maize in the semiarid areas.