Effects of shallow groundwater table and fertilization level on soil physico-chemical properties, enzyme activities, and winter wheat yield

Waterlogging adversely affects winter wheat (Triticum aestivum L.) growth by deteriorating soil environmental factors. The objective of this study is to test the effects of groundwater depth and fertilization level on soil properties, enzyme activities, and wheat yield. Experiments were carried out in micro-lysimeters at the groundwater depths of 0.2, 0.4, 0.5, 0.6, and 0.8 m under low, normal, and high fertilization levels in the winter wheat growth season from Oct. 2015 to May 2016. Soil water content, pH, organic matter content, total N, available P, available K as well as sucrase, urease, and phosphatase activities were measured in various growth stages of winter wheat, and yield component and grain yield were also measured after its harvest. Results indicated that soil water content and pH decreased with the increased groundwater depth. The lower contents of soil organic matter and nutrients appeared when groundwater depth was 0.5-0.6 m. Sucrase in the heading stage, urease in the jointing stage, and phosphatase activities increased significantly with the increased groundwater depth. Grain yield increased with groundwater depth to its maximum or approximate steady value. Total N and available P contents and urease activity appeared to increase with fertilizer application rate but available K content showed a contrary tendency. Grain yield increased with fertilizer application rate, but the effect of fertilization level on grain yield was lower than that of groundwater depth. A significant interaction between groundwater depth and fertilization level on grain yield existed. Soil enzyme activities were significantly correlated with available P content, and phosphatase activity was correlated with soil water, pH, organic matter, total N, and available K contents. It can be concluded that controlling groundwater depth and appropriate fertilizer application level can improve crop growth environment and promote winter wheat growth and its grain yield.