Abstract:
Adoption of conservation tillage resulted in changes in soil properties, soil organic matter, soil nutrients. These soil
variables were strongly correlated and could not be explained independently by the univariate analysis. The objectives of the
study were to use the factor analysis for the identification of the factor pattern in soil properties and to examine the changes in
factor scores in no-till (NT), chisel plow (CP) and moldboard plow (MP) tillage systems at different depths after 8 years of the
tillage application and planting of corn and soybean on a sloping and previously eroded with a root restricting fragipan
Grantsburg soil. The soil samples from the 0 to -5 and -5 to -15 cm soil depths were analyzed for the Ca, Mg, K, P, aggregate
stability, particulate organic C, N and humified organic C and N. With factor analysis, 13 highly correlated soil variables were
grouped into three different uncorrelated factors, which accounted for the 78% total variance of the data. The soil organic factor
had high variable loading on aggregate stability, soil organic C and N contents in soil, POM and humified organic fractions.
This factor varied between tillage and represented the accumulation of soil organic matter and its effect on aggregation because
of the adoption of tillage. The soil exchange factor had high variable loading for the extractable Ca, Mg and CEC, and varied
with tillage and depth because of mixing due to plowing and stratification due to use of no-till treatment. The soil nutrient factor
had high variable loading on soil K and P and soil pH and varied between tillage treatments. The nutrient factor scores were also
affected by fertilizer application and its mixing by plowing in CP and MP. No-till, which lacks mixing, resulted in decrease in
availability of nutrients. This technique enables us to combine the correlated soil variables into three different groups and assess
the impact of soil management systems, soil depths and sampling years on these factors. In the NT, lack of tillage, resulted in
stratification of exchangeable bases, reduced availability of nutrients. However, it contributed to the maintenance of soil organic
matter and soil aggregation. The mixing of soil with plowing resulted in the uniform nutrient availability and exchange capacity
of soil in plow layer with the CP and MP systems. The plowing affected soil aggregation adversely due to decomposition of soil
organic matter and making soil more susceptible to erosion. The crop yield of maize and soybean were higher with NT system
than with CP and MP systems
