English

Gasper Mowo Jeremias,Oenema Oene,Janssen Bert,Mrema Jerome,Masuki Kenneth

doi:10.5897/jssem12.070

Abstract

The dissolution in hydrochloric acid of three phosphate rocks (PRs) from sub-Saharan Africa was studied in the laboratory and their agronomic effectiveness compared using soils from Tanzania, Ivory Coast, Kenya and Netherlands. The objective was to investigate the potential of the PRs in supplying phosphorus under conditions of limited and unlimited supply of protons (H+). The test crop was maize (Zea mais var. LG11). Results show that calcium carbonate content is an important factor determining differences between the PRs with respect to their effectiveness. They also show that (i) differences in the dissolution of the PRs manifested more at low than at high acid concentration, (ii) availability of enough protons is an important factor in PR dissolution, (iii) low rates of PRs should be more desirable than high rates and (iv) soil and plant factors have an important role in the effectiveness of a PR.   Key words: Phosphate rocks (PRs) effectiveness, extractable phosphorus, hydrogen ions concentration, calcium carbonate content, sub-Saharan Africa.&nbsp

Highlights

Phosphorus (P) is one of the nutrients often limiting crop production in sub-Saharan Africa where continuous cropping without use of fertilizers is common among smallholder farmers
Tilemsi phosphate rock (PR) as medium and Minjingu PR as medium to high in reactivity, but our results suggest that Minjingu and Khouribga PRs have a lower reactivity than Tilemsi
Appeared to be more reactive compared to Khouribga and Minjingu PRs, this was not reflected agronomically (Figure 2) given the limited supply of protons in the

Summary

Introduction

Phosphorus (P) is one of the nutrients often limiting crop production in sub-Saharan Africa where continuous cropping without use of fertilizers is common among smallholder farmers. The direct application of such locally available P source is seen by many workers as a viable alternative (Msolla et al, 2005; Arcand and Schneider, 2006; Biswas and Narayanasamy, 2006; van Straaten, 2006). Their effectiveness upon application to soil relies on the presence of protons (H+).

Methods

Results

Discussion

Conclusion