Assessment for nitrogen pollution loads from farmland, Japan, by objective yield and standard fertilizer usage

This research proposes an assessment for nitrogen (N) pollution loads potential from farmland, based on comparison of N in objective crop yields with standard fertilizer usage. N in the objective yield was calculated using the “Standard Table of Food Composition in Japan”. Three findings were made by considering yields removed from farmland. First, paddy rice and beans have a low pollution potential, with rice paddies showing a negative pollution potential for N (around −14 kg/ha). Second, almost all vegetable and orchard crops tested had a high pollution potential for N, although this differed from crop to crop. Third, our outcomes align well with farmland pollution potential and non-absorbed nitrogen (NAN) as defined by Nishio, although the latter and indices rely on a laborious and complicated method. The correlation coefficients were 0.745 (R 2 = 0.555). These outcomes show the effectiveness of our proposed assessment for potential environmental pollution loads.