Interaction effect of nitrogen and vermicompost in the presence of herbicide (Clodinafop propargyl) on nitrogen transformation in a sandy soil

A laboratory experiment with three levels of nitrogen (0, 100 and 200 mg kg-1), two levels of vermicompost (0 and 1 % on dry wt. basis) and two levels of herbicide (0 and 60 g a.i. ha-1) was conducted with sandy soil of Hisar to study the interaction of nitrogen and vermicompost in the presence of herbicide (clodinafop propargyl) on nitrogen transformation during 2014. NH4+-N contents increased upto the 14th day in soil and then declined up to 56th day under control. NO3--N content in soil increased significantly throughout the incubation study under control. With con-junctive use of nitrogen along with vermicompost, NH4+-N contents increased significantly in the soil upto 14th day of incubation with an increase from 44.49 to 73.22 mg kg-1 and 64.00 to 102.87 mg kg-1, whereas NO3--N content in soil significantly increased throughout the incubation study over control and the increase was from 13.68 to 101.36 mg kg-1 and 23.19 to 115.48 mg kg-1. However, NH4+-N and NO3--N decreased significantly at all incubation periods with the application of herbicide alone and in presence of nitrogen as well as vermicompost. The study revealed that judi-cious use of N, leads to more availability of N to crop and prevents the environmental pollution. Higher levels of N application may increase the risk of ground water pollution due to more availability of NO3- ion which can be sub-jected to leaching losses. Vermicompost proved to be the important source of nutrients as it has narrow C:N ratio and decompose more quickly than other organic manures such as FYM etc. Among commonly used herbicides, clodinafop propargyl is most commonly used herbicide and may have negative impact on the microbial population and thus may hinder the transformation processes particularly in sandy soils which have low organic matter content and thereby affecting the availability of nutrients to crop and play decisive role in crop yields.