Improved Corn Yields When Humic Acid Extracted from Composted Manure Is Applied to Acid Soils with Phosphorus Fertilizer

Most corn planted on tropical acidic soils suffers substantial yield loss caused by low crop phosphorus (P) uptake. Humic acid is recommended to increase P uptake since it capable of competing with be bound soil adsorption complexes. extracted from composted manure (MHA) a good alternative humic because more reactive and has higher complexation ability compared leonardite. Therefore, the effectiveness soil-applied MHA combined was evaluated improve yields in aspect nutrient efficiency physiological performance. Two high-yielding cultivars that are highly accepted Indonesian farmers resistant downy mildew disease were subjected five different types combinations. The amount fertilizer equivalent 120 mg P2O5 kg?1 soil. H10P1 produced most significant result p < 0.05 terms total dry weight, grain yield. highest for leaves grains found H5P1, respectively. Although chlorophyll content not substantially improved, stomatal apertures 7 weeks after planting (WAP) significantly increased id="M2"> H15P1. photosynthetic rate nitrate reductase (NR) activity at 10 WAP id="M3"> H5P1 H10P1, results clearly indicated increases performance aperture, rate, NR can contribute yields.