Effects of fertilization and film mulching on soil physical and chemical properties and winter wheat yield on the Loess Plateau

ObjectivesThis study aimed to investigate the effects of different agricultural measures on increasing winter wheat yields and the physical and chemical properties of shallow soil, which would provide support for the selection of suitable measures for sustainable development in the Loess Plateau.

MethodsA winter wheat field experiment since 2002, located in Weibei dryland, was used to in this study. Six treatments were chosen, no fertilization control (CK), nitrogen and phosphate fertilization (NP), nitrogen and phosphate and potash fertilization (NPK), nitrogen and phosphate plus biochar addition (NPB), nitrogen and phosphate and half plastic-film mulching over the growth period (NPFG), nitrogen and phosphate and half plastic-film mulching over the summer fallow period (NPFF). Plough after harvest and before sowing of winter wheat was performed in all the six treatments. The physical and chemical properties and agronomic indexes of winter wheat in different treatments were investigated.

ResultsCompared with CK, NP could significantly improve the saturated hydraulic conductivity(Ks) of the shallow soil layer, reduce the soil compaction in 0–7.5 cm, significantly increase the water consumption of winter wheat growth period, improve the water use efficiency and precipitation utilization efficiency; at the same time, the contents of organic matter, total nitrogen, nitrate nitrogen, ammonium nitrogen, total phosphorus and available phosphorus in shallow soil were significantly increased, which increased the yields of winter wheat significantly. Compared with NP, total porosity of NPK in harvest stage were increased, and water use efficiency was increased significantly. At the same time, NPK improved soil total nitrogen and organic matter contents, and increased leaf area index of winter wheat significantly. Eventually the average yield of winter wheat was about 4500 kg/hm² in recent 3 years. Compared with NP, NPB reduced soil bulk density significantly (1.16 g/cm³), while increased soil porosity which caused that the Ks was 0.049 cm/min, and improved water use efficiency. The contents of soil organic matter, total nitrogen, total phosphorus and available phosphorus were increased, on the contrary, soil pH was decreased, which leading to increase of winter wheat yield. Compared with NP, NPFG and NPFF reduced the saturated hydraulic conductivity of the shallow soil layer significantly, increased soil compaction and water use efficiency of wheat, increased the contents of organic matter, ammonium nitrogen and available potassium, and reduced soil total phosphorus and pH. Removing the year of hail disaster, the yields of winter wheat maintained at 4700–4800 kg/hm².

ConclusionsLong-term conventional tillage and nitrogen and phosphorus fertilization significantly increase the yields of winter wheat, but result in decrease of soil pH. Based on the combined application of N and P, the application of biochar could significantly improve soil physical and chemical properties and increase the yields of winter wheat, however, its economic input is high. Combined application of potash, and half mulched the soil with plastic-film over the growth period would improve the soil nutrient status in the shallow layer, and increase economic benefits to a certain extent, which is thought to be suitable measure for winter wheat in the Loess Plateau.