Effects of phosphorus fertilizer sources on cowpea and subsequent cereal crop productivity in semi-arid West Africa

1999 ◽  
Vol 132 (1) ◽  
pp. 45-60 ◽  
Author(s):  
N. MULEBA ◽  
M. COULIBALY

A natural rock phosphate, ‘Kodjari” (RP), sparingly soluble, indigenous to Burkina Faso, and a commercial single superphosphate (SSP) fertilizer were studied at Farako-Bâ in the Northern Guinea Savannah (NGS) and at Oipasse in the Sudan Savannah (SS) regions of Burkina Faso. A 3-year crop sequence either of cowpea, maize and sorghum or of cowpea, sorghum and sorghum was used, respectively, in the NGS and SS regions. The sorghum crop in the third year was not fertilized with any phosphorus (P) source. The objectives of the research were to study the direct and residual effects of the P fertilizers on soil fertility improvement in order to boost agricultural productivity in both regions.Cowpea daylength-insensitive cultivars, in both regions, and maize and sorghum in the NGS and SS regions, respectively, responded more strongly to SSP than to RP fertilizer treatments. The optimum rate of SSP and RP source was 21·8 kg P/ha and 43·6 kg P/ha, respectively, for cowpea in both regions. The optimum rates of phosphorus fertilizer applied in the second year to maize in the NGS and to sorghum in the SS region, in addition to the optimum rate of P applied to cowpea the previous year, was 10·9 kg P/ha of SSP or 43·6 kg P/ha of RP, and 21·8 kg P/ha of SSP or 43·6 kg P/ha of RP, respectively. Both P sources had significant residual effects for up to 2 years. The agronomic effectiveness of RP relative to SSP, in the year of application of both fertilizers, was greater for cowpea than for maize in the NGS region and similar for cowpea and sorghum in the SS region; it increased markedly for the two subsequent cereal crops in both regions. Cowpea fertilization with both P sources proved, therefore, to be effective in improving the soil fertility and boosting the productivity of cereal crops in the 3-year crop sequence.

2004 ◽  
Vol 20 (6) ◽  
pp. 683-691 ◽  
Author(s):  
Bruno Hérault ◽  
Pierre Hiernaux

The soil seed bank in a 5-y-old Sahelian fallow was studied through seed extraction and compared with germinations recorded either in controlled conditions, ex situ in a glasshouse, or in the field. The influence of phosphorus fertilizer and mulch application during the preceding crop period, and that of seasonal grazing regimes applied the last 2 y of fallowing, were assessed on the composition of the seed stock. Ctenium elegans, Fimbristylis hispidula, Merremia pinnata and Phyllanthus pentandrus accounted together for 75% of extracted seeds, 72% of ex situ, and 62% of in situ seedlings. Mulch treatment was correlated with the first axis of the canonical correspondence analyses performed on the seedling datasets. Mulch and phosphorus fertilizer treatments held similar responses, as they both favoured the seed bank of erect dicotyledons such as P. pentandrus and Cassia mimosoides. On the whole, the effects of grazing remained modest compared with the residual effects of past crop management practices. However, seedling densities increased as a result of dry-season grazing, while the soil seed bank decreased with wet-season grazing. Grazing also reduced the spatial heterogeneity of the seed bank rather than the overall number of species.


2001 ◽  
Vol 58 (1) ◽  
pp. 165-170 ◽  
Author(s):  
Luís Ignácio Prochnow ◽  
José Francisco da Cunha ◽  
Ariel Francisco Candiotti Ventimiglia

Ten P fertilizers were collected (commercial fertilizers) or synthesized (experimental sources) in order to obtain single superphosphates varying in water and citrate solubility. A standard source of P was also produced by crystallization of the water-soluble fraction of a triple superphosphate. Eleven P sources were band applied to a medium textured Xanthic Hapludox, in Bahia, Brazil (low content of resin-extractable P) at a rate of 80 kg ha-1 of NAC + H2O (neutral ammonium citrate plus water) soluble P2O5, with soybean as the crop which was grown to maturity. A check plot (control) was included in the study. Three of the P sources [single superphosphate produced from Araxa phosphate rock (PR), low-grade single superphosphate produced from Lagamar PR and the standard source of P] were also applied at rates to provide 40 and 120 kg ha-1 of NAC + H2O soluble P2O5. Yield of soybean was evaluated by analysis of variance with mean comparison performed utilizing LSD lines, considering the P sources applied at a rate of 80 kg ha-1 of P2O5 + control. Regression procedures were used to study the relation between yield of soybean and rates of P2O5. The fertilizers tested performed equally well as a source of P for soybean. The level of water-soluble P did not influence fertilizer performance.


2000 ◽  
Vol 80 (1) ◽  
pp. 63-69 ◽  
Author(s):  
Selamyihun Kidanu ◽  
D. G. Tanner ◽  
Tekalign Mamo

A trial was conducted on an Ethiopian Vertisol from 1990 to 1995 to determine the residual effects of fertiliser N applied to tef [Eragrostistef (Zucc.) Trotter] on the grain and straw yield, N content, and total N uptake of succeeding crops of durum wheat (Triticum turgidum var. durum) and tef. The mean agronomic efficiency of 60 kg fertiliser N ha−1 was 13.1 kg grain kg−1 fertiliser N applied in the current year and 5.4 kg grain kg−1 fertiliser N applied in the previous year. Thus, the residual fertiliser N benefit was equivalent to 41.2% of the response to current season N application for the two cereal crops. The mean rates of apparent recovery of fertiliser N were 65.8% for current season N application and 31.0% for previous season N application. Soil organic matter and nitrate levels increased linearly in response to both previous and current season N application rates. The current study demonstrates that the residual effect of fertiliser N enhanced the yields and N contents of the grain and straw of both wheat and tef, resulting in a significant increase in total N uptake. Any analysis of the profitability of fertiliser N response should reflect the multi-year benefit period. Key words: N recovery, N residue, N uptake, tef, wheat


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