Humic Products in Various Soil Types and Weather Stresses.

Humic products, including humic acid, have a good history of positive response on crop growth on many crops.  However, there are always experiments where humic acid does not show a positive response and many more where the response is positive but not enough of a difference to show a statistically significant positive response.   A data base from many trials throughout the world has been developed over several years that includes different soil types and different climatic conditions.  Trials were established on different soil types with varying organic matter content and different sand, silt, and clay contents to determine if there is a response due to soil characteristics.  Results in corn and soybeans show that positive results occur more often on soil types that are weathered or considered poorer soils.  Many trials were established in locations without irrigation.  Some of these trials from the USA and Brazil occurred in corn and soybeans during years where drought or other weather conditions put stress on the crop.  There is a high correlation of positive response from humic acid when crops were grown in a high stress environment. The distinction of sites by soil type and stress level may help explain the seeming inconsistence of some of the humic products results.