Dynamics of manganese adsorption and desorption in soil under long-term farm yard manure and nitrogen application

A long-term field experiment on compensation of fertilizer nitrogen (N) through use of farm yard manure (FYM) on pearl millet (B)-wheat (W) sequence was undertaken since October 1967 at Research Farm of the Department of Soil Science, CCS Haryana agricultural university, Hisar. The treatments of the experiment consisted of three doses of FYM (15, 30 and 45 mg/ha/year) applied in three different months i. e. in summer bajra (B), in winter wheat (W) and in both the seasons (B+W). The control treatment of FYM (F₀) was also included. These 10 treatments (three FYM levels x three modes of FYM+one control) were assigned in main plots and each main plot was divided into three sub-plots receiving nitrogen at the rate of 0, 60 and 120 kg/ha applied through urea. All the treatments were replicated four times. The present study was conducted to assess the sorption phenomena of Mn in the soil after about 35 years of start of the experiment. Soil samples were collected from only two out of three levels of nitrogen i. e. 0 and 120 kg N/ha and from two out of four replications. Sorption studies were made using Langmuir and Freundlich adsorption isotherms. The parameters of these equations were calculated to describe the adsorption phenomena.