Effects of inorganic and organic amendment on soil chemical properties, enzyme activities, microbial community and soil quality in yellow clayey soil.

Zhanjun Liu,Qinlei Rong,Wei Zhou,Guoqing Liang,Jorge Paz-Ferreiro

doi:10.1371/journal.pone.0172767

Abstract

Understanding the effects of external organic and inorganic components on soil fertility and quality is essential for improving low-yielding soils. We conducted a field study over two consecutive rice growing seasons to investigate the effect of applying chemical fertilizer (NPK), NPK plus green manure (NPKG), NPK plus pig manure (NPKM), and NPK plus straw (NPKS) on the soil nutrient status, enzyme activities involved in C, N, P, and S cycling, microbial community and rice yields of yellow clayey soil. Results showed that the fertilized treatments significantly improved rice yields over the first three experimental seasons. Compared with the NPK treatment, organic amendments produced more favorable effects on soil productivity. Notably, the NPKM treatment exhibited the highest levels of nutrient availability, microbial biomass carbon (MBC), activities of most enzymes and the microbial community. This resulted in the highest soil quality index (SQI) and rice yield, indicating better soil fertility and quality. Significant differences in enzyme activities and the microbial community were observed among the treatments, and redundancy analysis showed that MBC and available N were the key determinants affecting the soil enzyme activities and microbial community. The SQI score of the non-fertilized control (0.72) was comparable to that of the NPK (0.77), NPKG (0.81) and NPKS (0.79) treatments but significantly lower compared with NPKM (0.85). The significant correlation between rice yield and SQI suggests that SQI can be a useful to quantify soil quality changes caused by different agricultural management practices. The results indicate that application of NPK plus pig manure is the preferred option to enhance SOC accumulation, improve soil fertility and quality, and increase rice yield in yellow clayey soil.

Highlights

Yellow clayey soil covers an area of 1.4 × 106 hm2 in southern China [1]
The concentrations of AP and AK were generally highest under NPK plus pig manure (NPKM) and NPK plus straw (NPKS), respectively
Our results demonstrated that the highest soil quality index (SQI) score was under NPKM (Fig 7)

Summary

Introduction

Yellow clayey soil covers an area of 1.4 × 106 hm in southern China [1]. the low organic matter content and nutrient availability in this soil have resulted in low crop productivity [2]. Increasing demand for food supply or security in this region requires enhancing the soil quality to improve crop production. The combination of chemical fertilizer with organic materials showed great potential for SOC sequestration in the paddy soils of southern China [9], especially soils with low levels of organic matter [10]. Yuan et al (2014) found that rice straw retention was effective for increasing SOC and improving soil fertility and productivity in yellow clayey soils [16]. These studies focused on the individual effects rather than combination effects, of specific organic amendments on soil physicochemical properties. Information about the differences in biological responses to chemical fertilizer and organic manure remains limited

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Discussion

Conclusion