Effect of Herbicides Application on Soil Physico-chemical Properties and Performance of Maize in Sudan Savanna Zone of Nigeria

A multi-locational field trial was conducted at two locations (Orchard of the Bayero University Gezawa village in Gezawa Local Government area) in the Sudan savanna zone of Nigeria to investigate the effect of applications of paraquat and atrazine herbicides on soil physico-chemical properties and maize performance. Pre-planting and plot-by-plot soil samples was taken 24 hours after herbicides application, vegetative growth period, reproductive stage and at harvest were taken and subjected to routine analyses using standard laboratory methods. Crop growth and yield characters were measured using standard methods. The experiment consisted of 7 treatments laid out in a randomized complete block design replicated 3 times. Results indicated highly significant differences between the locations in the content of the sand, silt and clay separates but no significant differences were observed between the treatments. There were highly significant variations in soil reaction, electrical conductivity, organic carbon, total nitrogen, available phosphorus and all the exchangeable bases, except calcium at both locations. Soil reaction, electrical conductivity, organic carbon, total nitrogen, available phosphorus, calcium, magnesium, potassium, sodium and cation exchange capacity showed no significant differences with all the treatments across the locations. Electrical conductivity, organic carbon, total nitrogen, available phosphorus and sodium were low across the locations but were higher at Bayero University Kano. The soils at both locations were generally acid. Thus, the soils at both locations were non-saline and non-sodic. Only the yield varied with the treatments. The highest yield was obtained at Bayero University Kano. Application of the highest treatment (4 kg/ha Atrazine + 4 kg/ha Paraquat was associated with high sand content and strong soil acidity). Combined application of 3 kg/ha Atrazine + 3 kg/a Paraquat was associated with low total nitrogen and exchangeable potassium and with the highest yield of maize. Application of Atrazine at 3 kg/ha corresponded with low organic carbon and low leaf area. Paraquat applied at 4 kg/ha was associated with very low concentration of exchangeable Na and moderate concentration of available P. Combined application of paraquat at 4 kg/ha was associated with low cation exchange capacity. Combined application of 3 kg/ha atrazine and 3 kg/ha paraquat is recommended for higher maize yield. Integrated soil fertility management is recommended in the study areas.