Corn cobs as fertilizers
NEXT to rice, white corn is the choice staple food of about 14 million Filipinos and yellow corn is used as a major feedstock for feeds. According to the data released by the Bureau of Agricultural Statistics (BAS), as of the first quarter of 2014, the country was able to produce 2.28 million metric tons (MT) of corn, a 1.33 percent higher than the last year production.
But these are just the kernels. The corn cobs are disposed.
Corn cob is the part of the corn ear on which the kernels grow. In the Philippines, corn cobs are commonly utilized as fuel. “May nag-suggest na gamitin na panggatong ang corn cobs. Pero kahit gamitin na fuel marami pa rin ang nakatambak na cobs sa mga processing plants at tumatambak din yung nakukuha nilang ash. So bakit di natin isipin ang ibang paggagamitan nito?” said Dr . Apolonio M. Ocampo, university researcher at the Crop Science Cluster, College of Agriculture, University of the Philippines Los Baños (UPLB).
There are sporadic cases noted wherein the corn cobs are used as fertilizer.
As there are no scientific literatures to support the effectiveness of corn cobs as fertilizer, it cannot be officially recommended to the corn farmers to use their unutilized cobs as fertilizer, thus, a scientific research was initiated to explore the potential of the corn cobs as alternative source of potassium (K) fertilizer. This UPLB-led research is funded by the Bureau of Agricultural Research (BAR).
The project objectives are to: 1) identify and evaluate corn cultivars and the contribution of corn cobs in terms of available potassium and other nutrient contents; 2) evaluate the effectiveness of corn cobs and ashes derived from commercial corn dryers and farmer’s fields when used as K-source and determine the period of time required for the K to be available to plants when applied to the field; and 3) determine the economics of using corn cobs and/or ashes as substitute source for the potassium fertilization of white corn.
Four-season field fertilizer trials were done in UPLB experiment station and the two largest corn producing provinces: Isabela and Bukidnon. This is in collaboration with the Cagayan Valley Research Center (CVRC) and the Northern Mindanao Integrated Agricultural Research Center (Nomiarc).
Result of the study showed that using the corn cob rates of 0, 5, 10, 15 and 20 tons cobs per hectare (tons cobs/ha), the grain yield from commercially K-fertilized plots and plots that used corn cobs showed no significant difference. “Sa nakita namin, maganda ang resulta. Maganda ang ani halos kapareha nung pagnilagyan mo ng inorganic potassium. Ang tinatagnan na lang namin ay kung gaano kadami ang natitira na potassium sa lupa pagkaraan ng apat na season or kada season. So yun ang ginagawa namin ngayon” explained Dr. Ocampo, project leader.
The study recommended that for white open pollinated variety (OPV) 10-15 tons cobs/ha should be used, while for hybrid corn, 20 tons cobs/ha is recommended to get a grain yield that is comparable to those of K-fertilized plots.
From the farmer’s perspective, a corn farmer in Mindanao averaging a harvest of 6-8 tons/ha can get a 1.2 – 3 tons of cobs. Though not enough to cover the K-fertilization of a hectare corn farm, it can still help decrease the production cost of farmers as muriate of potash when commercially purchase cost is around Php 1,800. Also, the application is easier as the farmer have to only scatter in his corn field the corn cobs or ash during the land preparation.
The farmers can also use the corn cobs extracts as foliar spray or liquid fertilizer by soaking it for four to five weeks in water. However, the proponents are still determining the right amount of dilution for optimum effectiveness.
With fertilizers getting a huge chunk of the production cost, farmers must have options for cheaper alternatives while still maintaining or better yet, increasing their profits. Research such as this, wherein a supposedly farm waste or crop residue can still be converted into something functional is an important step towards a sustainable practice of agriculture.