Current and Potential Humic Product Management in Production Agriculture of the U.S. Southwest.

Recent field data indicate the use of humic acid products in production agriculture in the U.S. Southwest and globally is exciting and, at times, very exciting. Replicated trials by universities and private research companies confirm that the application of Global Organics liquid humic acid products to lettuce in Arizona and pimiento peppers and strawberries in California will boost yields. Exchangeable and soluble sodium in soil were one half to two thirds less than a grower standard in Ventura, California pimiento peppers. Water penetration was easily improved in orange grove soils east of Clovis (CA). Both microbial numbers and diversity were increased in treated versus untreated plots in Arizona cantaloupes and California broccoli. Test data from Ventura (CA) celery introduced researchers to the vagaries of in-field humic acid product treatments. The trial was conducted for the competitive inhibition of two common celery diseases: Sclerotinia sclerotium (pink rot) and Rhizoctonia solani (crater rot). The incidence of disease was very limited in the trial and neither of the treatments (Botran, Humega®) significantly reduced the incidence of pink rot or crater rot over the untreated check. However, the use of the Humega® yielded a 9% increase in harvest weight. Humic acid has traditionally been used as an add-on application to a conventional fertilization program. Yet a Romaine lettuce trial on a university field station in Arizona demonstrated that the highest yield was obtained with Humega® and nitrogen at the lowest dose (30 kgN/ha). This is an interesting result, as growers could save a nitrogen application with the application of this humic acid product (common practice; in lettuce 60 kgN/ha). An application rate of 100cm-3 humic acid per palm tree per year plus 50% of a conventional fertilizer treatment was found to be the agronomically and economically optimum rate for mature oil palm planted on low fertility, acidic soils (pH < 5.0). This replicated 5 year trial was in Riau Province, Indonesia. These reproducible benefits of humic acid products for a wide range of crops in diverse settings indicate a fundamental effect on plant growth.