A Soil Organic Nitrogen Fraction that Reduces the Need for Nitrogen Fertilization

Abstract

The need to estimate mineralization has long been recognized in making N fertilizer recommendations, but little progress has thus far been made in identifying a specific fraction of soil organic N that affects crop responsiveness to N fertilization. After eliminating major defects in the methodology employed to fractionate the N in soil hydrolysates, a study was conducted to compare N‐distribution analyses for soils differing in N‐fertilizer responsiveness by corn (Zea mays L.). Hydrolyses with 6 M HCl were performed on composite soil samples (0–30 cm) that had been collected in late March or early April of 1990, 1991, or 1992, from 18 sites in a N‐response study involving 75 site–years throughout Illinois with different soil types, crop rotations, and N management practices. Concentrations of amino sugar N were 33 to 1000% greater (P < 0.001) for 11 nonresponsive than for seven responsive soils, whereas no consistent difference was observed in their content of total hydrolyzable N, hydrolyzable NH4–N, or amino acid N. Upon aerobic incubation for 3 mo with biweekly leaching, production of (NH4 + NO3 + NO2)‐N averaged 260% greater for three nonresponsive soils than for two responsive soils, and was accompanied by a net decrease in amino sugar N but not in amino acid N. Soil concentrations of amino sugar N were very highly correlated with check‐plot yield (r = 0.79***) and fertilizer‐N response (r = −0.82***). On the basis of amino sugar N, all 18 soils were classified correctly as responsive (<200 mg kg−1) or nonresponsive (>250 mg kg−1) to N fertilization.

Rhizobium leguminosarum bv. viciae sp. inoculation improves the agronomic efficiency of N of common bean (Phaseolus vulgaris L.)

“…This might causes ineffectiveness of inoculated Rhizobium sp. (Li et al 2009) and less response to N application (Mulvaney et al 2001). Regardless of N rates of application, all N rates of application gave significantly higher TBY than the control in both Rhizobium inoculation treatments at Hirna site.…”

A lagged variable model for characterizing temporally dynamic export of legacy anthropogenic nitrogen from watersheds to rivers

“…Stable isotopic tracers (mainly 3 H) have shown that delivery times for surface runoff, soil water/shallow groundwater, and groundwater to river systems are on the order of months, years, and decades, respectively (Iqbal 2002;Phillips and Lindsey 2003;Sanford and Pope 2013;Tesoriero et al 2013). Incorporation of N into soil organic matter and subsequent release of this N for potential leaching to the hydrosphere is also estimated to require several years to decades (Mulvaney et al 2001;Sebilo et al 2013). Estimated magnitudes of lag time by the LVM (~11 years) and by the statistical model developed for the Mississippi River watershed (~9 years; McIsaac et al 2001) are an average of all processes delaying N delivery from the watershed to the river outlet.…”

Organic nitrogen distribution in seven Tunisian soil types under contrasting pedogenetic conditions

“…Recently, new concerns have been raised about the adverse effects of N on the environment mainly because of high application rates of N fertilizers and improper land management practices (St Luce et al 2011). Groundwater contamination by nitrates has become a worldwide concern (Mulvaney et al 2001). Thus, to improve the efficiency of N uptake by plants and reduce massive use of N mineral fertilizers, we need an accurate prediction of N supply from soil organic matter (SOM) in both natural and agricultural ecosystems (Bhogal et al 2001).…”