Preliminary assessment of arbuscular mycorhizal inoculation in teak and napier grass agroforestry practice treated with soil amendments

Abstract Soil amendments are known to improve soil structure, increase moisture content, improve fertility and facilitate soil microbial functions. The objective of this study was to determine the effects of gypsum on colonization of arbuscular mycorrhizas in teak plantations planted as fences for napier grass. Teak seedlings were planted in October 2019 and divided into 4 blocks, A, B, C and D comprising 32 seedlings. Plots of A and C were treated with treatments of 3 kg of gypsum and 3 kg of compost (1:1), whereas B and D were control plots. NPK fertilizer was applied at every seedling at the rate of 0.05 kg for all blocks. Seedling heights and mean basal diameter (mm) were assessed at 9 months after planting. Soil samples for microbial study were taken before and after planting at 30 cm depth and screened for mycorrhizal spores and roots at the end of the experiment. Increased values for seedling heights and mean basal diameter (20-35%) were recorded for treatments B and C. Results pointed out that the amount of spore percentages were somewhat reduced in C and D and a slight increase was seen in treatments A and B. Root inoculation percentages in A and C were somewhat higher (1- 6%) as compared to B and D (0.5%). Early findings point out that application of gypsum and composts were not detrimental to the microbial population of arbuscular mycorrhiza as these treatments showed higher presence of hyphae and vesicles in fine roots and did not hamper physical growth. The role of soil amendments needs to be further investigated in terms of enhancing soil microbial population.