Rational Phosphorus Application Facilitates the Sustainability of the Wheat/Maize/Soybean Relay Strip Intercropping System.

Yuanxue Chen,Kaiwei Xu,Jing Liu,Chaochun Zhang,Ke Wang,Junyu Lu,Tao Zhou,Wenju Liang

doi:10.1371/journal.pone.0141725

Abstract

Wheat (Triticum aestivum L.)/maize (Zea mays L.)/soybean (Glycine max L.) relay strip intercropping (W/M/S) system is commonly used by the smallholders in the Southwest of China. However, little known is how to manage phosphorus (P) to enhance P use efficiency of the W/M/S system and to mitigate P leaching that is a major source of pollution. Field experiments were carried out in 2011, 2012, and 2013 to test the impact of five P application rates on yield and P use efficiency of the W/M/S system. The study measured grain yield, shoot P uptake, apparent P recovery efficiency (PRE) and soil P content. A linear-plateau model was used to determine the critical P rate that maximizes gains in the indexes of system productivity. The results show that increase in P application rates aggrandized shoot P uptake and crops yields at threshold rates of 70 and 71.5 kg P ha-1 respectively. With P application rates increasing, the W/M/S system decreased the PRE from 35.9% to 12.3% averaged over the three years. A rational P application rate, 72 kg P ha-1, or an appropriate soil Olsen-P level, 19.1 mg kg-1, drives the W/M/S system to maximize total grain yield while minimizing P surplus, as a result of the PRE up to 28.0%. We conclude that rational P application is an important approach for relay intercropping to produce high yield while mitigating P pollution and the rational P application-based integrated P fertilizer management is vital for sustainable intensification of agriculture in the Southwest of China.

Highlights

Food security, resource saving and environmental safety are focuses of globally many governments’ attention, especially Chinese government
The apparent recovery efficiency of fertilizer P in W/M/S system In China only 15–20% of the applied P is taken up by crops during the growing season [7,8], but the present results showed a greater P recovery efficiency (PRE) of the W/M/S system, on average 24.8%, or even higher, 28.0% when this system is applied with the critical P application rate, 72 kg P ha-1 (Table 3)
The overall apparent recovery of fertilizer P (PRE) of the W/M/S system is greatly increased comparing with the national average

Summary

Introduction

Resource saving and environmental safety are focuses of globally many governments’ attention, especially Chinese government. During the period 1960 to 2008, the total grain production of China increased 3.4 fold from 110 to 483 million tons [1], but P fertilizer input increased 91 fold during the same period [2]. Grain production greatly increased because of this substantial P fertilizer input, but excessive P use by farmers led to low P use PLOS ONE | DOI:10.1371/journal.pone.0141725. Phosphorus Management in Intercropping System efficiency, high environmental risk and P accumulation in soils which occurred in most regions of China [3,4]. In China, the total net P input during the period from 1980 to 2007 was 242 kg ha-1, causing soil Olsen-P increase from 7.4 to 24.7 mg kg-1 [6] while the P recovery efficiency (PRE) is currently only 15–20% [7,8]. About 9.3% of China’s arable land exceeded 40 mg kg-1 of Olsen-P in soil [6] and about 60% of inland lakes showed eutrophication, and 67% of the P source resulting in water pollution was derived from agriculture [10]

Methods

Results

Conclusion