Effects and Mechanisms of Phosphate Activation in Paddy Soil by Phosphorus Activators

Huanli Yao,Junying Yang,Jiale Hong,Jihong Li,Xian Chen,Xiaoyun Mao,Yueming Hu

doi:10.3390/su12093917

Abstract

Phosphorus (P) build-up in agricultural soils as a consequence of excessive P fertilizer application necessitates the exploration of soil P pool for crop supply. We conducted a soil incubation experiment, pot experiments, and field experiments to study the effects of different P activators (Pas) (humic acid, lignosulfonate sodium, and biochemical humic acid) on soil phosphate fraction, rice yield, and P loss. Through chemical analyses and microbial community structure measurement, we found that Pas significantly increased paddy soil water-soluble P (WSP), available P, Fe-P, and relative abundances of P-mineralizing and P-solubilizing microorganisms, whereas they decreased Al-P and microbial alpha diversity. Our pot experiment results showed that the application of Pas significantly reduced soil P loss and resulted in grain yield comparable to those obtained by fertilization with P fertilizers, and significantly higher than those in the control plants. The results of the field experiment suggested that Pas are able to increase rice yield more significantly than P fertilizers and improve the P utilization efficiency of rice plants. We conclude that application of Pas was more effective in reducing P leaching, soil total P, WSP, and Olsen P than P fertilizers during rice harvest.

Highlights

Phosphorus (P) is an essential nutrient for plant growth, and is often applied to most agricultural soils to increase crop production [1]
The increasing trend of Olsen P in paddy soil was stable when biochemical humic acid (BCHA) was added during the cultivation period, and the content of Olsen P was the highest among the three activators from day 45 to day 60, which was consistent with the best results obtained for rice growth (Table 2)
The results of the present study showed that for cultivated land with rich available P, the use of PAs 100% instead of P fertilizers could significantly reduce the amount of P loss (Figure 4) and meet the requirements of rice P nutrition in order to ensure the yield (Table 2)

Summary

Introduction

Phosphorus (P) is an essential nutrient for plant growth, and is often applied to most agricultural soils to increase crop production [1]. P fertilizers have played an important role in replenishing soil available P and promoting crop growth. When applied to soil, P fertilizers are rapidly fixed by ions such as calcium (Ca), aluminum (Al), and iron (Fe), thereby becoming sparingly bioavailable [2]. Until 2010, 5.9 Mt of P had accumulated in the soils of the cultivated lands in China, with an average of 240 kg ha−1, which is approximately ten times higher than the average in 1980 [3,4]. In the agricultural soils of South China, P accumulates at an annual rate of approximately 68 kg ha−1 [4,5]

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