Trichoderma harzianum Modulates Phosphate and Micronutrient Solubilization in the Rhizosphere

The availability of nutrients in the soil is dependent on soil health. Trichoderma is a beneficial microorganism responsible for sustainable agriculture that improves soil health and nutrient availability. Soil samples were collected from the field of the Agricultural Research Institute (ARI) Mingora Swat and amended with Trichoderma, single super phosphate (SSP), rock phosphate (RP), and compost. Both SSP and RP were added at the rate of 100 kg P ha⁻¹ soil, compost was applied at 20 ton ha⁻¹, and Trichoderma was added at a rate of 4 g kg⁻¹ soil. Experimental pots were arranged in a completely randomized design with three replicates and eight treatments. Treated and control pots were incubated for 112 days at room temperature and moisture level, at field capacity. Soil samples were collected after 7, 14, 28, 56, and 112 days to determine the effect of treatments on ammonium bicarbonate–diethylenetriaminepentaacetic acid (AB-DTPA)-extractable P and micronutrients. The results showed that the maximum value of extractable P was noted in treatment Trichoderma + SSP + compost, which increased with time but with no with consistent trend, and was maximal at 112 days. Maximum Zn and Mn concentrations were noted with the treatment Trichoderma + SSP + compost at 112 days after incubation. Maximum Cu was noted in samples amended with Trichoderma + SSP + compost at time interval 7 days, while Fe content was maximal in samples treated with Trichoderma + RP + compost and an incubation interval of 28 days. The interaction between treatments and time interval was also significant for phosphorus and micronutrients. By comparing the different treatments, it was observed that Trichoderma + SSP + compost was an effective combination to enhance the availability of micronutrients in soil. It was also obvious from the results that the availability of nutrients was higher when Trichoderma was applied alone or in combination. Therefore, Trichoderma should be applied to the soil to enhance soil health and nutrient availability without deleterious effects on environmental quality.