Trade-offs between the short- and long-term effects of residue quality on soil C and N dynamics

Abstract

The decline of soil organic matter (SOM) and its associated fertility is one of the most important constraints to enhanced crop productivity in subSaharan Africa. Integrated soil fertility management recognizes the potential benefits of the combined use of organic residue and mineral fertilizer inputs for improved crop yield and SOM build up. However, these benefits may be controlled by residue quality. We examined the short-to long-term C and N dynamics following application of different quality residues with and without N fertilizer in a series of experiments comprising different timescales of measurement in a Kenyan Humic Nitisol. The combined results of these studies indicate that residue quality and fertilizer additions alter short-term C and N mineralization. Combining low quality residue and fertilizer inputs immobilized a greater amount of fertilizer-N than high quality residue. Under field conditions, this reduction in available N induced by the combination of low quality residue and fertilizer reduced environmental N losses and created a positive interactive effect on crop N uptake. While input management manipulated short-term nutrient dynamics, it did not influence long-term SOM stabilization. The input of residue, regardless of quality, contributed to long-term soil fertility improvement. In conclusion, organic residue quality can be manipulated to optimize short-term nutrient dynamics while still conferring the same benefits to long-term SOM contents.

Fate of 15N-labeled Inorganic Fertilizer in an Upland Soil Applied with Sweet Sorghum Bagasse and N Uptake Efficiency by Komatsuna Plants

“…In this study, application of SSB showed a tendency to increase the N distribution from applied IF to the plant and soil, thereby decreasing the rate of unaccounted N (SUR/SSB: 18%, INC/SSB: 19%, INC/IF: 46% in Table 6). This result implies that a combination of organic matter of a high C/ N ratio with IF has positive effects on the soil, air environment, and soil fertility, and is in agreement with previous reports on reduction of environmental N losses by crop residue and IF inputs (Gentile et al, 2009(Gentile et al, , 2011.…”

“…This may be because of the N immobilization that occurred when applying SSB with a high C/N ratio, regardless of the application method (i.e., surface application or incorporation). The N supply potential to komatsuna was lower in the soil with both IF and SSB compared to that with IF alone, supporting the hypothesis suggested by Gentile et al (2011). However, the dry weight/N uptake ratio (Table 5) and dry weight of group, followed by the INC/SSB and INC/IF groups, but no significant difference was found among the 3 treatments.…”

“…However, N immobilization in the soil to which these materials have been applied might offer several advantages, including retention of inorganic N in the soil and decreased nitrate leaching and denitrification. Several reports have shown that the combination of crop residues with high C/N ratios and IF inputs reduces environmental N losses and creates a positive interactive effect on crop N uptake (Gentile et al, 2009(Gentile et al, , 2011. Moreover, mulching with high C/N organic matter has positive effects to control weeds, increase infiltration, reduce evaporation, supply available nutrients, and increase crop yields (Othieno, 1973;Gaur and Mukherjee, 1980;Ssali et al, 2003).…”

Soil Organic Carbon and Nitrogen After Application of Nine Organic Amendments

“…Similarly, Bhogal et al (2011) found that manure was quickly stabilized and increased SOC for more than 2 yr. A major difference between wheat and legume residues or manure would be in N content. In a study comparing residues of low and high N content, Gentile et al (2010) found that they gave the same SOC result after a number of years, with or without fertilizer N additions. Furthermore, Gregorich et al (1997) concluded that fertilizer did not affect the turnover of either the free or physically protected light fraction organic matter, and the location of organic matter in the soil aggregates was a main factor in its susceptibility to decomposition.…”

Photodegradation for Nutrient Management in the Dry Tropics

“…Efficient use of organic residues as fertilizers is therefore important, and there is a large literature on this topic [1,2]. Particularly high quality plant litter and residues that can release most of their nutrients during peak crop growth are valuable.…”