Soil Nutrients and Grain Yield Performance in Spring Wheat (<i>Triticum aestivum</i>) as Influenced by Regulated Deficit Irrigation

Abstract

A field trial was conducted in 2007 and 2008 to investigate the difference in soil nutrients and grain yield of spring wheat (Triticum aestivum) as influenced by regulated deficit irrigation (RDI) in an arid area. Three RDI treatments and a no-water-deficit control (CK) were designed to subject wheat to various degrees of soil water deficit at different crop developmental stages. Significant differences (p<0.05) occurred in soil organic matter (SOM) and soil available potassium (SAK) contents in both growing seasons, but no difference (p>0.05) occurred among the RDI treatments. Meanwhile, no differences were found in soil total nitrogen (STN) and soil total phosphorus (STP) contents among the treatments and CK. SOM content was improved by 6.2% to 7.2% in RDI treatments than in the CK over the two growing seasons, while the STN, STP, and SAK contents were increased by 1.2% to 2.5%, 1.4% to 5.6%, and 9.0% to 11.2%, respectiely. The STP (t=10.900, p<0.001), soil available phosphorus (SAP, t=8.894, p<0.001), and SAK (t=11.706, p<0.001) contents in 0~40 cm soil layer at wheat harvest were significantly lower in 2008 than in 2007, while the SOM (t=-2.513, p<0.05) and STN (t=-9.950, p<0.001) contents were significantly higher in 2008. Soil organic C, STN, and SAP balance was greatly influenced by RDI in two growing seasons. Compared to the no-water-deficit control, grain yields over the two years were respectively improved by 16.5% to 24.9% in RDI plots.The relationship between grain yield and the soil nutrients was described as y=15843.4 +713.3SOM-20989.1STN+38.7SAN-15.0SAP-39.7SAK (R2=1, p<0.001).