Nitrogen recovery as influenced by soil type and moisture regime

Environmental concerns has led to renewed interest in N management to maximize crop yield and minimize pollution potential. Experiments were conducted over a four year period at three locations in Illinois to evaluate the effects of soil type, N application rate, and soil moisture conditions on N loss potential and consequently corn (Zea mays L.) yield. At each location, a factorial arrangement of four N rates (0, 112, 168, and 224 kg N ha$\sp{-1}$) and three soil moisture levels (ambient, ambient + 100 mm, and ambient + 150 mm of excess water) was established. Application of $\sp{15}$N tagged fertilizer N was made in microplots inside the 168 kg N ha$\sp{-1}$ plots. After the moisture treatments were imposed and moisture levels allowed to return to less than field capacity, plots were split with each half receiving either 0 or 56 kg ha$\sp{-1}$ supplement N application. Fertilizer recovered from the plant-soil system on a Drummer sicl ranged from 37 to 53% with the application of excess water compared to 80 to 88% with the ambient treatment. Recoveries on a Cisne sil ranged from 56 to 67% with 150 mm of excess water and 80 to 95% with the ambient treatment. Recoveries on a Plainfield s ranged from 4 to 13% with 150 mm of excess water and 18 to 70% with the ambient treatment. Greatest N losses were attributed to denitrification on the Drummer sicl and Cisne sil, and to leaching on the Plainfield s. Models relating corn yield, soil NO$\sb3$, plant N, and total recovered N to soil moisture condition and N application were constructed for each site. The number of days above soil tension of $-$0.033 MPa was the best measure of soil moisture condition correlated to the dependent variables on the Drummer sicl and Cisne sil, while total rainfall plus irrigation in May and June was best on the Plainfield s.U of I OnlyETDs are only available to UIUC Users without author permissio