Irrigation has more influence than fertilization on leaching water quality and the potential environmental risk in excessively fertilized vegetable soils.

Yang Li,Juanqi Li,Lihong Gao,Yongqiang Tian,Wen-Xiong Lin

doi:10.1371/journal.pone.0204570

Abstract

Excessive fertilization is a common agricultural practice that often negatively influence soil and environmental quality in intensive vegetable production systems in China. To reduce negative effects of excessive fertilization, current studies generally focused on fertilizer management but not irrigation. In this study, we investigated the effects of fertilization and irrigation on soil properties, leaching water characteristics, plant growth, cucumber yield, irrigation water use efficiency (IWUE) and partial factor productivity of nitrogen (PFPN) in a double cropping system. The treatments included (i) conventional irrigation with conventional N fertilization (IcNc), (ii) optimal irrigation with conventional N fertilization (IoNc), (iii) conventional irrigation with optimal N fertilization (IcNo), and (iv) optimal irrigation with optimal N fertilization (IoNo). In general, fertilization merely influenced concentrations of nitrate (NO3-), phosphorus (P) and potassium (K), but did not affect most leaching water characteristics. In contrast, irrigation influenced pH, EC and concentrations of P, K, Ca, Mg, Na and Cu. Cumulative leached amounts of NO3-, P, K, Ca, Mg, Na, Fe, Cu and Zn were significantly decreased by optimal irrigation as compared to conventional irrigation under same fertilization conditions, but not by optimal fertilization as compared to conventional fertilization under same irrigation conditions. The leachate volume was strongly positively correlated with cumulative leached amounts of all tested elements, and these relationships were obviously influenced by irrigation but not fertilization. The IoNo treatment significantly increased both IWUE and PFPN as compared to the IcNc treatment. However, the IcNo treatment only enhanced PFPN, while the IoNc treatment improved IWUE, when compared to the IcNc treatment. Our results suggested that irrigation has more influence than fertilization on leaching water quality and that the optimal irrigation combined with optimal fertilization was efficient in reducing the potential environmental risk caused by excessive fertilization in intensive vegetable production systems.

Highlights

IntroductionChina’s arable land accounts for only about 7% of the cultivated land in the world
China’s population accounts for approximately 19% of the world’s population
The aims of this study were to examine (1) whether nutrient leaching caused by excessive fertilization can be reduced by optimal irrigation, (2) how leaching water quality and plant growth may be affected by conventional excessive and/or optimal fertilization and irrigation, and (3) quantify the amount of nutrient elements in leaching water under both excessive and optimal irrigation and fertilization conditions

Summary

Introduction

China’s arable land accounts for only about 7% of the cultivated land in the world. Since the early 1980s, Chinese agriculture has intensified greatly on a limited land area with large inputs of fertilizers, and has obtained relatively high crop yields on limited land [1]. Solar greenhouse is a common vegetable cultivation facility in China. To obtain high crop yields, Chinese farmers often apply excessive fertilizers and irrigation water during crop production. In some greenhouse vegetable cultivation regions in China, annual irrigation rate was as high as 1000 mm, and fertilizer N apparent recovery efficiency was only 18–33% of applied N taken up by the vegetables. Redundant water and fertilizers can cause serious environmental problems, such as greenhouse gas emission, soil degradation, freshwater contamination, and natural resource consumption [5,6]

Objectives

Methods

Results

Conclusion