Influence of Cereal-Legume Rotation on Striga Control and Maize Grain Yield in Farmers’ Fields in the Northern Guinea Savanna of Nigeria

On-farm trials were conducted in 2001, 2002, and 2003 in the northern Guinea savanna of Nigeria to evaluate integrated Striga hermonthica control measures under farmermanaged conditions. These included intercropping a Striga-resistant maize variety with cowpea for 3 years and also cropping this maize in rotation with legume trap crops - soybean and cowpea for 1-2 two years. Intercropping Striga-tolerant maize variety, Acr. 97TZL Comp. 1-W, with cowpea (Vigna unguiculata L.) consistently reduced Striga infestation in maize relative to continuously cropped sole maize over the threeyear period. Maize grain yield was lower in the intercrop than in the sole maize plot probably due to competition from cowpea. However, because of the high value of cowpea in the intercrop, crop value for this system was higher than sole cropped maize. Legume-maize rotation reduced Striga infestation by 35% after one year of legumes in the rotation and by 76% after two years of legumes in the rotation. Soybean was more effective in reducing Striga infestation and also gave higher maize grain yield than cowpea. The rotation of these two legumes with maize had clear advantage over continuously cropped maize. Farmers should therefore be encouraged to adopt the introduction of grain legumes into the cereal cropping systems of the Nigerian savanna

A meta-analysis of long-term effects of conservation agriculture on maize grain yield under rain-fed conditions

Conservation agriculture involves reduced tillage, permanent soil cover and crop rotations to enhance soil fertility and to supply food from a dwindling land resource. Recently, conservation agriculture has been promoted in Southern Africa, mainly for maize-based farming systems. However, maize yields under rain-fed conditions are often variable. There is therefore a need to identify factors that influence crop yield under conservation agriculture and rain-fed conditions. Here, we studied maize grain yield data from experiments lasting 5 years and more under rain-fed conditions. We assessed the effect of long-term tillage and residue retention on maize grain yield under contrasting soil textures, nitrogen input and climate. Yield variability was measured by stability analysis. Our results show an increase in maize yield over time with conservation agriculture practices that include rotation and high input use in low rainfall areas. But we observed no difference in system stability under those conditions. We observed a strong relationship between maize grain yield and annual rainfall. Our meta-analysis gave the following findings: (1) 92% of the data show that mulch cover in high rainfall areas leads to lower yields due to waterlogging; (2) 85% of data show that soil texture is important in the temporal development of conservation agriculture effects, improved yields are likely on well-drained soils; (3) 73% of the data show that conservation agriculture practices require high inputs especially N for improved yield; (4) 63% of data show that increased yields are obtained with rotation but calculations often do not include the variations in rainfall within and between seasons; (5) 56% of the data show that reduced tillage with no mulch cover leads to lower yields in semi-arid areas; and (6) when adequate fertiliser is available, rainfall is the most important determinant of yield in southern Africa. It is clear from our results that conservation agriculture needs to be targeted and adapted to specific biophysical conditions for improved impact

Mapping the drivers of parasitic weed abundance at a national scale : a new approach applied to Striga asiatica in the mid‐west of Madagascar

The parasitic weed genus Striga causes huge losses to crop production in sub‐Saharan Africa, estimated to be in excess of $7 billion per year. There is a paucity of reliable distribution data for Striga ; however, such data are urgently needed to understand current drivers, better target control efforts, as well as to predict future risks. To address this, we developed a methodology to enable rapid, large‐scale monitoring of Striga populations. We used this approach to uncover the factors that currently drive the abundance and distribution of Striga asiatica in Madagascar. Two long‐distance transects were established across the middle‐west region of Madagascar in which S. asiatica abundance in fields adjacent to the road was estimated. Management, crop structure and soil data were also collected. Analysis of the data suggests that crop variety, companion crop and previous crop were correlated with Striga density. A positive relationship between within‐field Striga density and the density of the nearest neighbouring fields indicates that spatial configuration and connectivity of suitable habitats is also important in determining Striga spread. Our results demonstrate that we are able to capture distribution and management data for Striga density at a landscape scale and use this to understand the ecological and agronomic drivers of abundance. The importance of crop varieties and cropping patterns is significant, as these are key socio‐economic elements of Malagasy cropping practices. Therefore, they have the potential to be promoted as readily available control options, rather than novel technologies requiring introduction

Economic Analysis Of Striga (Striga hernonthica ) Management Strategies In Sudan, Northern Guinea And Southern Guinea Savanna Zones Of Nigeria

The witchweed, Striga hernonthica, which attacks cereal crops grown by subsistence farmers, can result in massive yield reduction in maize, sorghum, millet, upland and hungry rice and sugarcane. Estimated crop losses due to Striga in the Northern Guinea Savanna of Nigeria is up to 5-6 million US dollars annually, with attendant negative impact on the livelihood of about 60% of the farming population. Striga tolerant maize varieties aimed at reducing the losses and increasing farmers\' income have been developed. On-farm demonstrations were conducted in three agro-ecological zones of Nigeria during the 2005 cropping season. The objectives of the demonstrations were to create awareness and promote the adoption of the improved Striga tolerant maize genotype among farmers. The Striga tolerant maize varieties, Acr. 97TZL Comp.1-W, SYN2000EE-W, 99TZEE-Y STR CO, EVDT STR CO, and Acr. 94TZE Comp.5-W was compared with farmers\' varieties. Data were collected through the administration of structured questionnaire, and the data were analyzed using descriptive statistics and budgeting technique. This paper determines the costs and returns and describes farmers awareness and reasons for choice of the improved Striga control technologies.. The costs and returns analysis indicated that labor and fertilizer inputs accounted for greater parts of the total variable costs incurred in all the varieties. Labor cost of the improved Striga tolerant maize varieties and farmers\' varieties were 58, 57, 54, 54% and 61 and 65%, respectively while fertilizer cost were 37, 37, 40, 40%, while the farmers\' varieties were 38 and 41%, respectively in Sudan Savannah. In Northern and Southern Guinea Savannahs, labor accounted for 43 and 36% of improved maize, while the farmers\' variety was represented by 44 and 36%. Fertilizer cost accounted for 50 and 54% of the total cost production for the Striga tolerat maize variety and 51 and 55 % for farmers\' varieties. It was also found that cultivation of Striga tolerant maize varieties ( SYN2000EE-W) and farmers\' variety in Sudan Savanna was not profitable as indicated by a negative gross margin, while 99TZEE-YSTRCO,EVDSTRCO and ACR.94TZE Comp.5-W had positive gross margins. In Northern Guinea and Southern Guinea Savanna the improved Striga tolerant maize variety had positive gross margin of N1, 039.18 and N111, 040.40/ha, while for farmers variety , the gross margin was negative in Northern Guinea Savanna compared to a gross margin of N721, 981.20/ha in Southern Guinea Savanna. Keywords: Striga, Management strategy, Economic, Analysis and adoption studies Journal of Agriculture, Forestry and the Social Sciences Vol. 4 (2) 2006: pp. 60-6

Effects of sole cropping, intercropping and rotation with legume trap-crops on striga control and maize grain yield in farmers' fields in the Guinea savannas

On-farm trials were conducted in 2001 to 2003 in the northern Guinea savanna of Nigeria to evaluate integrated Striga hermonthica control methods under farmer-managed conditions. These included intercropping a Striga-resistant maize variety with cowpea (Vigna unguiculata L.) and also cropping this maize in rotation with legume trap-crops - soybean (Glycine max (L) Merr.) and cowpea. Intercropping Striga-tolerant maize vaeirty, Acr. 97 TZL Comp. 1-W, with cowpea or rotating it with the soybean cultivar TGX1448-2E) or the cowpea cultivar IT93K452-1 proved effective in reducing Striga incidence and infestation compared with three years of continuously cropped maize as control. Striga incidence was reduced by 73% in intercropped maize, 64% in maize after two years soybean, and by 68% in maize after two years of cowpea than in continuously cropped maize. However, maize grain yield was considerably reduced when intercropped with cowpea, probably due to competition from the cowpea crop. Maize grain yield was 28% higher after one year of soybean and 21% higher after one year of cowpea than in the continuously cropped maize. Maize grain yield was 85% higher after two years of soybean, and 66% higher after two years of cowpea than in the continuously cropped maize

Response of soybean genotypes to Alectra vogelii infestation under natural field conditions

Field studies were conducted in 1995 and 1996 in the northern Guinea savanna of Nigeria to determine the response of 22 soybean genotypes to Alectra infestation. Significant differences were observed amongst soybean genotypes in number of Alectra shoots that emerged at 9 and 10 weeks after sowing and days to first Alectra emergence. Alectra emergence occurred later in early maturing soybean genotypes [54 days after sowing (DAS)] while with most late maturing genotypes, Alectra emergence started at 50 DAS. Result revealed that sixteen genotypes supported few or no Alectra shoots while six were susceptible. Soybean genotypes that supported high numbers of Alectra shoots recorded lower grain yields than those with fewer Alectra shoots. However, soybean genotypes, SAMSOY2 and TGX1485-1D that significantly supported high numbers of Alectra recorded grain yields similar to those of genotypes that supported few or no Alectra. These findings may be due to three possible mechanisms of resistance of soybean genotypes to Alectra parasitism. The sixteen genotypes, which supported few or no Alectra shoots, may have produced lower amounts of root exudates required for stimulation of germination of Alectra. They may also have prevented the initiation, attachment, and penetration of haustorium from Alectra plants to the roots of the hosts. These mechanism were however, not investigated in this study. Further studies may therefore be necessary to confirm our speculations. Soybean genotypes, SAMSOY2 and TGX1485-1D, which recorded high yield irrespective of high infestation with Alectra may exhibit tolerance to the parasite

Influence of cereal legume rotation on Striga control and maize grain yield in farmers fields in the northern Guinea Savanna of Nigeria

On-farm trials were conducted in 2001, 2002, and 2003 in the northern Guinea savanna of Nigeria to evaluate integrated Striga hermonthica control measures under farmermanaged conditions. These included intercropping a Striga-resistant maize variety with cowpea for 3 years and also cropping this maize in rotation with legume trap crops - soybean and cowpea for 1-2 two years. Intercropping Striga-tolerant maize variety, Acr. 97TZL Comp. 1-W, with cowpea (Vigna unguiculata L.) consistently reduced Striga infestation in maize relative to continuously cropped sole maize over the threeyear period. Maize grain yield was lower in the intercrop than in the sole maize plot probably due to competition from cowpea. However, because of the high value of cowpea in the intercrop, crop value for this system was higher than sole cropped maize. Legume-maize rotation reduced Striga infestation by 35% after one year of legumes in the rotation and by 76% after two years of legumes in the rotation. Soybean was more effective in reducing Striga infestation and also gave higher maize grain yield than cowpea. The rotation of these two legumes with maize had clear advantage over continuously cropped maize. Farmers should therefore be encouraged to adopt the introduction of grain legumes into the cereal cropping systems of the Nigerian savanna

Response of Soybean Genotypes to Alecta vogelii Infestation under Natural Field Conditions

Field studies were conducted in 1995 and 1996 in the northern Guinea savanna of Nigeria to determine the response of 22 soybean genotypes to Alectra infestation. Significant differences were observed amongst soybean genotypes in number of Alectra shoots that emerged at 9 and 10 weeks after sowing and days to first Alectra emergence. Alectra emergence occurred later in early maturing soybean genotypes [54 days after sowing (DAS)] while with most late maturing genotypes, Alectra emergence started at 50 DAS. Result revealed that sixteen genotypes supported few or no Alectra shoots while six were susceptible. Soybean genotypes that supported high numbers of Alectra shoots recorded lower grain yields than those with fewer Alectra shoots. However, soybean genotypes, SAMSOY2 and TGX1485-1D that significantly supported high numbers of Alectra recorded grain yields similar to those of genotypes that supported few or no Alectra. These findings may be due to three possible mechanisms of resistance of soybean genotypes to Alectra parasitism. The sixteen genotypes, which supported few or no Alectra shoots, may have produced lower amounts of root exudates required for stimulation of germination of Alectra. They may also have prevented the initiation, attachment, and penetration of haustorium from Alectra plants to the roots of the hosts. These mechanism were however, not investigated in this study. Further studies may therefore be necessary to confirm our speculations. Soybean genotypes, SAMSOY2 and TGX1485-1D, which recorded high yield irrespective of high infestation with Alectra may exhibit tolerance to the parasite

Performance of diverse maize genotypes under nitrogen deficiency stress in the northern Guinea Savanna of Nigeria

Article purchasedThe Guinea savannas of Nigeria have a high potential for the production of maize because of favourable environmental conditions. Despite this high potential, the yields obtained in farmers' fields are still very low. This is due to soil degradation and nutrient depletion arising from intensification of land use. Nitrogen (N) is the major nutrient limiting maize production in the Guinea savannas where the use of inorganic fertilizers is low. One strategy for improving the productivity of maize is to select varieties that perform well under suboptimal soil N conditions. This study assessed the performance of diverse maize germplasm under a range of N levels. Growth and grain yields differed significantly between the genotypes at all N levels. These variations were more pronounced at zero and 30 kg N ha−1 than at 90 kg N ha−1. Grain yield under N-deficient conditions was correlated with an increased number of ears per plant, stay-green rating, leaf chlorophyll concentration, leaf area index, reduced anthesis–silking interval and reduced days to silking suggesting that these traits are linked to tolerance to N deficiency. One hybrid (Oba Super 2), the drought-tolerant genotypes and four maize genotypes previously selected for tolerance to N-deficient conditions performed better than the widely grown adapted controls under zero and 30 kg N ha−1. At zero N, the grain yield of maize decreased with advances in cycles of selection for tolerance to suboptimal N conditions suggesting that N deficiency in the selection environment was not sufficient to discriminate between genotypes. The good performance of drought-tolerant varieties under suboptimal N conditions suggests that selection for drought tolerance may confer tolerance to N-deficient conditions