Seedling characteristics and grain yield of maize grown under straw retention affected by sowing irrigation and splitting nitrogen use

Abstract

The practice of straw retention often causes seedling issues, including slow seedling establishment and weak seedling. Irrigation shortly after sowing (namely ‘sowing irrigation’, abbreviated as SI) may help to accelerate the seedling establishment under straw retention, and appropriate split nitrogen (SN) management may further boost crop growth and grain yield. Here, we conducted a 2-year field trial to assess the impacts of SI and SN on crop growth, grain yield and water and nitrogen use efficiencies of a maize hybrid i.e. Zhengdan 958 grown under straw retention. The treatments consisted of two irrigation conditions and three splitting nitrogen regimes, with three replications. SI treatment was composed of 0 mm irrigation (denoted as W0) and 60 mm irrigation (denoted as W1) shortly after sowing. SN management contained a similar total nitrogen rate (300 kg ha−1) but was split in three proportions between sowing and big flare stage, i.e. 10:0 (denoted as N1), 5:5 (denoted as N2) and 3:7 (denoted as N3). Our results indicated that sowing irrigation accelerated seedling emergence by 2–7 days, and increased grain yield by 4.73% (2014) and 5.90% (2015), and water use efficiency by 1.69% (2014) and 3.80% (2015) compared to the treatment without sowing irrigation. N2 and N3 treatments increased grain yield by 9.00–10.12% via greater kernel number, and increased nitrogen partial factor productivity by 9.35–10.20% in both years. The improved grain yield by sowing irrigation or splitting nitrogen was due to greater canopy photosynthetic capacity with higher leaf area index, leaf chlorophyll content and net photosynthesis rate. It was found that the optimal ratio of basal: topdressing nitrogen depended on whether sowing irrigation was used. Without sowing irrigation, W0N2 produced the highest grain yield; while with irrigation, both W1N2 and W1N3 produced a greater production than W1N1. In conclusion, the combination of sowing irrigation and splitting nitrogen to the big flare stage could increase not only maize grain yield, but also resource-use efficiency under straw retention in lime concretion black soil of Huaibei Plain, Anhui Province, China.