Evaluation of an agropastoral system introduced into soybean fields in Paraguay: Positive effects on soybean and wheat production
2010
Shimoda, K., Japan International Research Center for Agricultural Sciences, Tsukuba, Ibaraki | Horita, T. | Hoshiba, K. | Bordon, J.
Effects of an agropastoral system on the production of soybean and wheat were investigated by comparing, from 2003 to 2007, agropastoral plots that had been converted from 7-year pasture (guinea grass: Panicum maximum; 1996 to 2003) to crop cultivation, with control plots that had been continuously cropped over 10 years with soybean at the Japan International Cooperation Agency's Paraguay Agricultural Technology Center (CETAPAR-JICA). Soybean productivity in this area increased from 1979 until 1993, when yield peaked at 3.39 t/ha and then declined. In this study, soybean yields ranged from 1.48 to 3.56 t/ha in agropastoral plots and from 0.63 to 2.47 t/ha in control plots. In each year, the yield in the agropastoral plots was 1.1 to 2.4 times more than in the control plots. Wheat yields were also higher in agropastoral plots (1.59 to 3.17 t/ha) than in control plots (1.18 to 2.31 t/ha). In each year, yield in the agropastoral plots was 1.2 to 1.8 times more than in the control plots. Thus, soybean and wheat yields were sustained by introducing an agropastoral system. We also examined the chemical and physical properties of the soil under initial conditions in both plot types. The concentrations of phosphate, potassium and magnesium in surface soil in agropastoral plots were significantly lower than in control plots. The content of organic matter at soil depths of 0 to 60 cm in the agropastoral plots was significantly higher than in the control plots, and the physical properties of the agropastoral plot soil (gaseous phase, bulk density, and soil aggregates) were improved. We conclude that the agropastoral system positively affected all these properties.
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