A field experiment was conducted to assess the effect of irrigation regimes and Bradyrhizobium ja... more A field experiment was conducted to assess the effect of irrigation regimes and Bradyrhizobium japonicum strains on the performance of soybean cultivar TGX1440-IE. The study was carried out for two consecutive years during the dry season (February-May) at Tono Irrigation Project site in a Guinea Savannah zone of Ghana. Three irrigation regimes based on soybean crop water requirements (full or normal (W0), half (W1) and one and a half (W2) crop water requirements) and two strains of B. japonicum (LS-50 and TAL-120) along with one uninoculated treatments with three replications were laid out in a split-plot randomized complete block design. The LS-50 strain inoculated soybean (I2) had the highest value in the number of nodulation, growth, yield and WUE, followed by the uninoculated (I0) and the TAL-120 (I1) had the least. The LS-50 strain significantly (P<0.01) increased the number of nodulation, growth, yield and WUE by 15 %, 14 %, 10 % and 12 % respectively over the uninoculated ...
A B S T R A C T Agricultural management practices are frequently non conservative and can lead to... more A B S T R A C T Agricultural management practices are frequently non conservative and can lead to substantial loss of soil organic carbon and soil fertility, but for many regions in Africa the knowledge is very limited. To study the effect of local agricultural practices on soil organic carbon content and to explore effective ways to increase soil carbon storage, field experiments were conducted on an upland rice soil (Lixisol) in northern Benin in West Africa. The treatments comprised two tillage systems (no-tillage, and manual tillage), two rice straw managements (no rice straw, and rice straw mulch at 3 Mg ha À1) and three nitrogen fertilizer levels (no nitrogen, 60 kg ha À1 , 120 kg ha À1). Phosphorus and potassium fertilizers were applied to be non-limiting at 40 kg P 2 O 5 ha À1 and 40 kg K 2 O ha À1 per cropping season. Heterotrophic respiration was higher in manual tillage than no-tillage, and higher in mulched than in non-mulched treatments. Under the current management practices (manual tillage, with no residue and no nitrogen fertilization) in upland rice fields in northern Benin, the carbon added as aboveground biomass and root biomass was not enough to compensate for the loss of carbon from organic matter decomposition, rendering the upland rice fields as net sources of atmospheric CO 2. With no-tillage, 3 Mg ha À1 of rice straw mulch and 60 kg N ha À1 , the soil carbon balance was approximately zero. With no other changes in management practices, an increase in nitrogen level from 60 kg N ha À1 to 120 kg N ha À1 resulted in a positive soil carbon balance. Considering the high cost of inorganic nitrogen fertilizer and the potential risk of soil and air pollution often associated with intensive fertilizer use, implementation of no-tillage combined with application of 3 Mg ha À1 of rice straw mulch and 60 kg N ha À1 could be recommended to the smallholder farmers to compensate for the loss of carbon from organic matter decomposition in upland rice fields in northern Benin.
A field experiment was conducted to assess the effect of irrigation regimes and Bradyrhizobium ja... more A field experiment was conducted to assess the effect of irrigation regimes and Bradyrhizobium japonicum strains on the performance of soybean cultivar TGX1440-IE. The study was carried out for two consecutive years during the dry season (February-May) at Tono Irrigation Project site in a Guinea Savannah zone of Ghana. Three irrigation regimes based on soybean crop water requirements (full or normal (W0), half (W1) and one and a half (W2) crop water requirements) and two strains of B. japonicum (LS-50 and TAL-120) along with one uninoculated treatments with three replications were laid out in a split-plot randomized complete block design. The LS-50 strain inoculated soybean (I2) had the highest value in the number of nodulation, growth, yield and WUE, followed by the uninoculated (I0) and the TAL-120 (I1) had the least. The LS-50 strain significantly (P<0.01) increased the number of nodulation, growth, yield and WUE by 15 %, 14 %, 10 % and 12 % respectively over the uninoculated ...
A B S T R A C T Agricultural management practices are frequently non conservative and can lead to... more A B S T R A C T Agricultural management practices are frequently non conservative and can lead to substantial loss of soil organic carbon and soil fertility, but for many regions in Africa the knowledge is very limited. To study the effect of local agricultural practices on soil organic carbon content and to explore effective ways to increase soil carbon storage, field experiments were conducted on an upland rice soil (Lixisol) in northern Benin in West Africa. The treatments comprised two tillage systems (no-tillage, and manual tillage), two rice straw managements (no rice straw, and rice straw mulch at 3 Mg ha À1) and three nitrogen fertilizer levels (no nitrogen, 60 kg ha À1 , 120 kg ha À1). Phosphorus and potassium fertilizers were applied to be non-limiting at 40 kg P 2 O 5 ha À1 and 40 kg K 2 O ha À1 per cropping season. Heterotrophic respiration was higher in manual tillage than no-tillage, and higher in mulched than in non-mulched treatments. Under the current management practices (manual tillage, with no residue and no nitrogen fertilization) in upland rice fields in northern Benin, the carbon added as aboveground biomass and root biomass was not enough to compensate for the loss of carbon from organic matter decomposition, rendering the upland rice fields as net sources of atmospheric CO 2. With no-tillage, 3 Mg ha À1 of rice straw mulch and 60 kg N ha À1 , the soil carbon balance was approximately zero. With no other changes in management practices, an increase in nitrogen level from 60 kg N ha À1 to 120 kg N ha À1 resulted in a positive soil carbon balance. Considering the high cost of inorganic nitrogen fertilizer and the potential risk of soil and air pollution often associated with intensive fertilizer use, implementation of no-tillage combined with application of 3 Mg ha À1 of rice straw mulch and 60 kg N ha À1 could be recommended to the smallholder farmers to compensate for the loss of carbon from organic matter decomposition in upland rice fields in northern Benin.
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