Changes in Soil Physicochemical Properties and Urease Activity as Affected by Reclaimed Water Irrigation and Nitrogen Fertilization

Abstract

【Objective】 Using treated wastewater as a supplementary water resource for irrigation is one solution to helping relieve the pressure resulting from water shortage in many regions around the world. Since reclaimed wastewater is rich in nutrients and elements that are beneficial and harmful to crops and soil microbial communities, the impact of reclaimed water irrigation on microbial activity and physicochemical properties of soil is likely to vary with other agronomic practices, which remains poorly understood. The purpose of this paper is to address these issues. 【Method】 The experiments were conducted in pots repacked with soil. The irrigation amount was the same in all pots, and every pot was irrigated four times after emergence and each time irrigated 1 L water, with nitrogen fertilization varying only(0, 120, 150, 180 mg/L). Clean water irrigation was taken as the control. During the experiment, we measured the change in nitrogen distribution and urease activity in each pot. 【Result】 Compared with the control, reclaimed water irrigation did not show significant effect on soil organic mass (SOM), total nitrogen (TN), ammonium, but reduced soil pH, electrical conductivity (EC) and water-soluble Na+ content. It also increased soil nitrate, water-soluble K+ and urease activity in the 0~10 cm soil layer, all at significant level. Soil physicochemical properties and urease activity in the 0~5 cm soil were negatively correlated with TN and water-soluble Na+, while positively correlated with water-soluble K+, all at significant level. 【Conclusion】 For all treatments we compared, reclaimed water irrigation coupled with 120 mg/kg of nitrogen fertilization was most beneficial to increasing soil nutrients and urea activity in the soil.

Keywords

• reclaimed water irrigation
• physicochemical properties
• nitrogen fertilization
• urease activity