Long-term straw incorporation benefits the elevation of soil phosphorus availability and use efficiency in the agroecosystem

摘要

Soil pH and organic matter are important factors influencing phosphorus (P) fertilizer use efficiency. Long-term crop straw incorporation alters soil pH and soil organic matter. To explore the influence of crop straw incorporation on P fertilizer use efficiency, this research was conducted in a long-term field experiment (30 years) with a wheat-soybean cropping system and selected four treatments: no fertilization, mineral fertilization (NPK), mineral fertilization + 3750 kg/ha wheat straw (WS/2-NPK) and mineral fertilization + 7500 kg/ha wheat straw (WS-NPK). Results show that long-term straw incorporation not only accentuates soil acidification, but also elevates crop yields and soil P availability. Consequently, compared with the NPK treatment, straw incorporation contributed to higher P fertilizer use efficiency, which increased from 43% in 1983 to 72% in 2012 for WS/2-NPK, from 46% to 69% for WS-NPK, and from 34% to 60% for NPK treatments, respectively. Moreover, the P fertilizer use efficiency in all fertilization treatments could be categorized as follows: slowly increasing stage in 1982-2002, stable stage in 2003-2006, and rapidly increasing stage in 2007-2012. Correspondingly, the annual P balances of the WS/2-NPK and WS-NPK treatments ranged from positive to negative in the 1982-2003 and 2004-2012. Therefore, compared with mineral fertilization alone, long-term wheat straw incorporation has the associated benefit of elevating the P fertilizer use efficiency. However, to maintain sustainable high crop productivity, it is necessary to elevate the dose of P fertilizer input and reduce the soil acidification under wheat straw incorporation.