Field Trials of Growmate Humic Products in Central and South America: Benefits of Networked Sites.

The effectiveness of humic products as crop and soil amendments deserves further study but remains in dispute.  Broad-based evidence for their performance could be gained through coordinated networks of sites that evaluate humic products under diverse soil and weather conditions and for several crop types.  One such network was begun by GrowMate International to study crop responses to their products, with sites in Brazil (four states), Costa Rica, Guatemala, Mexico (two locations), and Kansas (U.S.).  The crops being evaluated at multiple sites include corn (maize), sugar cane, soybean, and coffee, and at individual sites also banana, pineapple, potato, tomato, and others. Application rates at most sites ranged up to about 1 gallon/ha (3.8 liters/ ha). Crop growth responses are similar to those observed by researchers elsewhere, including yield increases averaging about 10% with yet bigger responses for tomato and potato, 15-20% increases in root growth, and elongated ears in corn.  For some crops, quality indices responded more so than did biomass, such as sugar concentration of pineapple. To better understand plant physiological mechanisms that lead to enhanced crop growth with humic product application, these sites will collaborate with an emerging global network of long-term sites.  Plant samples from the networked field sites will be analyzed by laboratory-based collaborators for traits including hormone concentrations, biochemical nature, and genetic signaling. The long-term nature of these sites will enable the study of benefits to soil health.