Corn Response to an Integrated Plant Nutrition System (IPNS) With Humic Acid and Biofertilizers

Sustainable agriculture production depends on the development of methods that optimize nutrient cycling, minimize use of external inputs, and maximize input use efficiency according to the conditions of each region. The principle of an integrated plant nutrition system (IPNS) is to tailor plant nutrition and soil fertility management, taking advantage of the combined and harmonious use of inorganic, organic and biological resources. This greenhouse study investigated the individual and combined use of inorganic, organic and biological fertilizer resources for corn (Zea mays L.). We evaluated the effects of commercial synthetic fertilizer, humic acid products, compost/manure teas and bioinoculant as inorganic, organic and biological resources, respectively, and their synergy on corn growth and soil respiration parameters under a period of water stress. The pots were laid out in completely randomized design and the total of sixteen treatment combinations were replicated four times. In general, when comparing to the control values, the use of humic acid (HA), biofertilizers and the integration of both compounds generated significantly greater early season plant height, chlorophyll content, photosynthetic efficiency and shoot/root dry biomass. The soil substrate induced respiration was affected by only one biofertilizer product at two different rates. Though all pots received adequate synthetic fertilizer, the control plants were generally smaller and less vigorous compared to the plants receiving either HA or biofertilizer treatments, but no additive benefit was observed for the integrated practice compared to individual applications. Further studies addressing different types and levels of stress along with greater stress duration should be conducted to validate these findings.