This article has been peer reviewed and accepted for publication. It is in production and has not been edited, so may differ from the final published form.
Intensive annual crop production and root development in a tropical acid soil under long-term no-till and soil amendments management
In tropical conservation agricultural systems, crop yield is limited by soil acidity and root growth inhibition, especially under intensive crop rotation. To improve soil fertility and crop yield in these areas, this study evaluated the effect of surface applications of lime and phosphogypsum. Four treatments were evaluated: control (without soil amendment application); phosphogypsum (2.1 + 2.1 + 2.1 Mg ha-1); lime (2.7 + 2.0 + 2.0 Mg ha-1); and a combination of lime and phosphogypsum (2.7 + 2.0 + 2.0 and 2.1 + 2.1 + 2.1 Mg ha-1, respectively) previously applied on 2002, 2004 and 2010, respectively. We evaluated the soil chemical properties, root development, plant nutrition, yield components, and grain yield of 10 crops in 4 years using 5 different species (Zea mays, Crambe abyssinica, Vigna unguiculata, Triticum aestivum and Phaseolus vulgaris). Our long-term results from this tropical region demonstrate the benefits of surface liming in alleviating subsoil acidity, reducing Al3+ toxicity, improving Ca2+ and Mg2+ availability, and increasing SOM accumulation in all soil profiles at depths up to 0.60 m. For maize and crambe, the effects of adding phosphogypsum included the increased development of the plants and reproductive structures, which increased the grain yield, and exhibited synergistic effects in association with lime for maize and common bean. For cowpea and wheat, adding phosphogypsum did not have an effect, whereas surface liming was essential to improve plant nutrition, grain yield, and wheat grain quality. The combination of both soil amendments is an important tool to reduce the soil acidification process, resulting in the highest levels of Ca2+ and Mg2+ and the highest base saturation values in the topsoil layers (0 to 0.20 m) over time. It is important to emphasize that our long-term results showed the viability of surface liming plus phosphogypsum for improving tropical soil fertility, which can reflect an increase in grain yield and contributes to the sustainability of agricultural systems under intensive land use in highly weathered areas.
CP17233 Accepted 08 February 2018
© CSIRO 2018