Site Specific Nutrient Management for Soft Corn Varieties in the Highlands of Guatemala

In 2010, the total number of experimental sites at Alta Verapaz grew to 10, which is five more than in 2009. The same experimental design was used, that is, a balanced fertilization treatment based on local experience against plots with individual omission of N and P. All experimental plots were planted with a population of 62,000 plants/ha arranged in rows 0.8 m apart and hills 0.4 m apart. Every hill received two seeds. This is the same planting arrangement used in 2009. The balanced treatment was 146-90-74 kg N-P₂O₅-K₂O/ha + 26 kg MgO, 43 kg S, 1.1 kg Zn, and 2.4 kg B/ha.

Grain yield from the 10 sites ranged from 2.7 to 4.6 t/ha for the complete treatment, with an average of 3.7 t/ha. The N omission plots ranged from 2 to 3 t/ha, averaging 1.6 t/ha, and the P omission plots from 1.5 to 4.2, averaging 2.7 t/ha. The high variation among sites is understandable given the hilly conditions of farmer fields and the natural adjustment to handling the new planting procedure. Some reasonable assumptions can be made from the accumulated data. It can be assumed that a yield of 4.5 t/ha is a realistic, attainable yield for the conditions prevalent in Alta Verapaz. More controlled experiments conducted in the region testing Zn sources have produced average yields greater than 5.5 t/ha, which has become the target yield for the immediate future. It can also be assumed that, in general, grain yields of around 1.5 t/ha can be obtained without N and 2.5 t/ha without P. Finally, it can also be assumed an agronomic efficiency (AE) of 20 kg of grain per kg of N used and 40 kg of grain per kg of P used. These numbers can be used as a reference for corn production in the region until more accurate figures are obtained.

This process will progressively fine-tune the fertilizer rates for the recommendation domain at Alta Verapaz. Improved crop and fertilizer management can lead to higher attainable yields, higher nutrient use efficiency, and a better economy for the local farmers. Guatemala-06