Maize response to K and gypsum in acid soils of Chiapas, Mexico

IPNI-2016-MEX-62

02 Jun 2018

2017 Annual Interpretive Summary


This Canpotex-supported project, was carried out in cooperation with Mexico's National Agricultural Research Institute (INIFAP) and the International Maize and Wheat Improvement Center (CIMMYT). The project began in 2016 to fine-tune potassium (K) and gypsum rates for maize production in the acid soils of La Frailesca (Chiapas). Four K application rates (0, 60, 120, and 180 kg K2O/ha) and four gypsum application rates (0, 1.25, 2.5, and 5 t/ha) were factorially applied at two farms on soils with 0.2 cmol/kg of exchangeable K. Based on previous experience that showed the efficacy of correcting soil acidity first, both experimental sites received a blanket dolomitic limestone application calculated to decrease exchangeable aluminum (Al) below 20% of the effective cation exchange capacity, which is the critical threshold for maize in the area.

Maize yield increased linearly from 6.5 to 8.2 t/ha, when 120 kg K2O/ha was added and stabilized afterwards. Likewise, the response to gypsum peaked at 8.3 t/ha, when 1.25 t gypsum/ha was applied, with no further yield increase at higher rates. These results are consistent with those obtained earlier under comparable soil, environmental, and management conditions, and have allowed local advisers to start planning the transfer of these technological options to farmers.