Effects of soil compaction and arbuscular mycorrhiza on corn (Zea mays L.) nutrient uptake

Soil compaction is of great importance, due to its adverse effects on plant growth and the environment. Mechanical methods to control soil compaction may not be economically and environmentally friendly. Hence, we designed experiments to test the hypothesis that use of plant symbiotic fungi, arbuscular mycorrhiza (AM) may alleviate the stressful effects of soil compaction on corn (Zea mays L.) growth through enhancing nutrient uptake. AM continuously interact with other soil microorganisms and its original diversity may also be important in determining the ability of the fungi to cope with the stresses. Hence, the objectives were: (1) to determine the effects of soil compaction on corn nutrient uptake in unsterilized (S1) and sterilized (S2) soils, and (2) to determine if inoculation of corn with different species of AM with different origins can enhance corn nutrient uptake in a compacted soil. Using 2kg weights, soils (from the field topsoil) of 10kg pots were compacted at three and four levels (C1, C2, C3 and C4) (C1=non-compacted control) in the first and second experiment, respectively. Corn (cv. 704) seeds were planted in each pot and were inoculated with different AM treatments including control (M1), Iranian Glomus mosseae (M2), Iranian G. etunicatum (M3), and Canadian G. mosseae, received from GINCO (Glomales In Vitro Collection), Canada (M4). Corn leaf nutrient uptake of N, P, K, Fe, Mn, Zn and Cu were determined. Higher levels of compaction reduced corn nutrient uptake, however different species of AM and soil sterilization significantly increased it. The highest increase in nutrient uptake was related to P (60%) and Fe (58%) due to treatment M4S2C3. Although it seems that M3 and M4 may be the most effective species on corn nutrient uptake in a compacted soil, M2 increased nutrient uptake under conditions (C3 and C4 in unsterilized soil) where the other species did not. Through increasing nutrient uptake AM can alleviate the stressful effects of soil compaction on corn growth.