Response of the maize-sesame-pigeon pea association to N, P, and K at La Máquina, Guatemala


29 Apr 2016

2015 Annual Interpretive Summary

The residual effects on maize and sesame of P and K applications made in 2014 were studied in 2015. No tillage was used to reduce the interactions between the two nutrients and the soil. In maize, significant positive effects on grain yield were determined from additions of P, but not from K applications, whereas sesame yields did not differ statistically with either P or K application timing or rates. The lack of response of both crops to K is consistent with the absence of K effects on yields reported for the 2014 season, which could be related to the soil’s exchangeable K concentration (0.4 cmol/kg). The lack of response of sesame to P could be due to it being planted between maize rows, with the P applied in a localized manner next to maize hills.

Average maize yield when no P was applied in 2014 and 2015 was 4,900 kg/ha, significantly lower than when 100 kg P2O5/ha (5,890 kg/ha) or 200 kg P2O5/ha (5,950 kg/ha) were applied in 2014 and no P was added in 2015. When P was reapplied in 2015 to plots that had been fertilized in 2014, the yields of maize tended to decrease in comparison to those from plots where P had been applied only in 2014. Yields were 5,160 and 5,010 kg/ha when 100 and 200 kg P2O5/ha were respectively applied to plots that had received 100 kg P2O5/ha in 2014. Both yields were significantly lower than when 100 kg P2O5/ha were applied in 2014 (5,890 kg/ha). Moreover, when 100 and 200 kg/ha of P2O5 were applied in 2015 after 200 kg P2O5/ha had been applied in 2014, the corresponding yields were 5,700 and 5,480 kg/ha, which are not statistically different than that measured when 200 kg P2O5/ha were applied in 2014 only (5,950 kg/ha).

In 2014, a positive maize response to P was significant at 200 kg P2O5/ha, a result that was probably influenced by the prevailing very dry conditions. There is evidence, however, that soils in this region have been influenced by the deposition of volcanic materials that bring about P fixation. Our results suggest the convenience of a rather heavy P application and avoidance of soil tillage, which seem to have significant positive effects on maize performance.