Direct interactions between N fertilizer and organic matter: evidence from trials with ¹⁵ N-labelled fertilizer.

Abstract

This paper focuses on testing the Direct Hypothesis using 15N-labelled fertilizers. This hypothesis formulated by Vanlauwe et al. (2001a) originates from data obtained under controlled laboratory conditions showing interactions between organic matter-C and mineral-N. A series of experiments (lysimeter, nanoplots and microplots) with 15N-labelled fertilizer (urea or ammonium sulfate) and organic matter was carried out to test the Direct Hypothesis at different scales. Details of the trials testing the Direct Hypothesis through the use of 15N-labelled fertilizers and organic matter carried on an Arenosol in Ibadan, southwestern Nigeria are discussed.

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

“…Similarly, in a lysimeter study, Vanlauwe et al (2002) observed a reduction in N leaching when fertilizer was combined with low quality maize residue but not with high quality M. pruriens. Therefore, low quality residues can be used in combination with fertilizer to reduce N leaching and nutrient losses to the environment.…”

“…As residue quality affects the rate of residue decomposition, quantity of N immobilization and timing of nutrient release (Heal et al 1997), it will likely influence the interaction between fertilizer and residues. For example, in a lysimeter study, Vanlauwe et al (2002) found that incorporating low quality (Zea mays L.) residue with N fertilizer reduced N leaching, but this effect was minor when fertilizer was combined with high quality Mucuna pruriens (L.) DC. residues.…”

Effect of plant biomass, manure and inorganic fertilizer on maize yield in the central Highlands of Kenya

“…Integration of inorganic and organic nutrient inputs could therefore be considered as a better option in increasing fertiliser use efficiency and providing a more balanced supply of nutrients. Vanlauwe et al, (2002) reported that combination of organic and inorganic nutrient sources result into synergy and improved conservation and synchronization of nutrient release and crop demand, leading to increased fertiliser efficiency and higher yields.…”

“…One of the approaches is the integrated nutrient management that combines use of organic inputs with chemical fertiliser. The beneficial effects of combined organic and inorganic sources on soil fertility, crop yields, and maintenance of soil organic matter have repeatedly been shown in field trials (Nandwa, 2003;Vanlauwe et al, 2002), yet there are no predictive guidelines for their management, such as those that exist for inorganic fertiliser. The success of combined nutrient management depends on several factors that include the types and quantities of organic materials available, and the rates and proportions at which the two nutrient sources are combined.…”

Adoption potential of selected organic resources for improving soil fertility in the central highlands of Kenya

“…Annual soil loss is high, estimated at 22 kg N ha -1 , 5 kg P ha -1 and 15 kg N ha -1 (Smaling et al 1997). To reverse the nutrient depletion in African soils, there has been renewed interest among researchers to promote the use of organic resources, with several authors reporting the materials ability to substitute or supplement mineral fertilizer (Vanlauwe et al 2002;Bationo et al 2004). The use of organic materials to replenish soil fertility is not new.…”