Soil Quality Dynamics during Different Growth Stages of Corn (Zea mays, L.) Cultivation in Sri Lanka

Maize known as Corn is popular among farmers as a cost effective crop with limited fertilizers. Cutting down natural forests for the planting of monocultures has had drastic impact on the soil quality leading to changes in soil properties. In Sri Lanka, no studies have been carried out to assess the effect on the properties of soil due to Maize although it is one of the extensive monoculture crops at present. The objective of the present study is to find out the effects on soil properties due to Maize cultivation during the different growth stages of the crop. This information is expected to assist in making decisions for sustainable soil management. Standard methods were used in measuring soil properties. % moisture, permeability, conductivity, Cation Exchange Capacity (CEC), the total organic carbon (Corg) and microbial biomass (Cmic) are significantly higher at seedling stage than the harvesting stage indicating possible impacts on the quality of soil. There are very little differences between growing and blooming stage for all the tested parameters. The data on effects are positively correlating with each other displaying possible consequences due to maize monoculture. The Cmic/Corg ratios of soils were low during both seedling and harvesting stages suggesting reduced number of microorganisms in soil. However, comparatively higher microbial action has been observed during both growing and blooming stages due to fertilizers. The lowest microbial respiration data during harvesting stage in the present study clearly indicates the impacts of maize plant on the biological quality of soil. Pearson’s Correlation Matrix for Soil Properties reveals that there are positive correlations for pH, Conductivity, CEC and % Organic Carbon between growth and blooming stage. Slightly negative correlation for the microbial biomass indicated that biological quality is very slowly decreasing from growth to blooming. Our results suggest that there is a very clear indication that soil is slowly deteriorating with the growth of Maize and this could lead to serious situation with continuous growth of the same plant as practiced by Sri Lankan farmers.