Soil water use and crop yield increase under different long-term fertilization practices incorporated with two-year tillage rotations

Water shortage and soil nutritionally depleted are the most limiting factors of crop production on the Loess Plateau. Conservation tillage rotation, conserved soil water and enhanced soil fertility effectively, produced high and stable crop yields in a spring maize-winter wheat-fallow rotation over a two-year period (hereafter called maize-wheat-fallow rotation). Corresponding and appropriate fertilization practices should enable the full potential of tillage rotation. Therefore, a long-term two-factor split-plot experiment (2007-2016) was established in Heyang County, Shaanxi Province, China, a typical rainfed dryland agricultural region. Beginning in 2007, three fertilization practices (balanced fertilization (BF), low fertilization (LF) and conventional fertilization (CF)) and four tillage systems (no tillage rotated with subsoiling annually (NS), subsoiling rotated with conventional tillage annually (SC), conventional tillage rotated with no tillage annually (CN), and continuous conventional tillage (CT)) were conducted to assess crop yield and soil water variation. The results showed that CCN (CF + CN, 5440 kg ha(-1)) and BNS (BF + NS, 8415 kg ha(-1)) produced the highest crop yield for winter wheat and spring maize, respectively. LNS (LF + NS, 419 mm) had a better soil water condition in fallow periods. NS and CN rotations had a better soil water condition (reserved more soil water for crop growth) than SC and CT during the wheat and maize growth season. However, both the average ET of winter wheat and spring maize under all of the treatments had no significant differences (P > 0.05) in ten years. In ten years, NS and CN rotations had higher water use efficiency (WUEs) than the SC rotation and CT, BNS had the highest WUE (19.0 kg ha(-1) mm(-1))for the spring maize - winter wheat rotation. Tillage rotation and fertilization had an interactive effect on soil water use and crop growth, and the results might clarify the response of crop yield and soil water variation to fertilization and tillage rotations. For further and sustainable development of crop production, BNS (5133 and 8415 kg ha(-1) for wheat and maize yield, respectively; soil water in fallow: 386 mm) and BCN (5221 and 8116 kg ha(-1) for wheat and maize yield, respectively; soil water in fallow: 388 mm) are recommended as the optimal fertilization and tillage rotations for rainfed crop production on the Loess Plateau.