Mycorrhizal Inoculation Effect on the Forage Cowpea Biomass Production in Burkina Faso

In Burkina Faso, breeding occupies an important place in the country’s economy, but is based essentially on the exploitation of the natural resources (pasture) which remains limited in extent due to the extension of land cultivated by agricultural practices extensive. Food is one of the most important limiting factors in animal production, hence the need to develop mechanisms to improve the production of food resources. This study is a contribution to fodder production improvement. In this study, cowpea was grown in a greenhouse for 60 days and inoculated with two inocula of arbuscular mycorrhizal fungi. The growth parameters were measured at 30 and 60 days after sowing. Shoot, root and total biomass were evaluated 60 days after sowing. The results show Yac 2 mix inoculum improves height growth (95.5%), height relative growth rate (525%), collar diameter (138%), collar diameter relative growth rate (328.57%), shoot biomass (396.3%), root biomass by (205.66%), total biomass by (320%), total nitrogen of aerial parts (92.39%) and total phosphorus of aerial parts (143.48%) compared to control. Yac 2 mix appears the most effective of all inoculum used in this study.

Pesticide Exposure Levels and Risk Assessment in Operators Involved in the Cashew Production in Côte d’Ivoire

To assess the level of producers’ exposure and the health risk in relation to phytosanitary practices in cashew crops in C?te d’Ivoire, a descriptive longitudinal toxicological study was conducted in 2018-2019 with 76 cashew producers in the areas of Mankono, Dabakala and Bondoukou. The data collected permitted the assessment of phytosanitary risks on the health of producers according to the Quebec-IRPeQ pesticide risk indicators. Field observations translated into scenarios were used to determine the exposure levels of producers via the UK-POEM predictive model. The main active substances used were glyphosate, 2,4-D, cypermethrin, acetamiprid, lambdacyhalothrin, profenofos, imidacloprid, deltamethrin, mancozeb and metalaxyl. The risk indicators showed that 2,4-D (TRI = 1332.25;SRI = 432.98), profenofos (TRI = 2550.25;SRI = 637.56) and mancozeb (TRI = 841;SRI = 147.18) among herbicides, insecticides and fungicides respectively could have more adverse health effects after exposure. These findings translated into scenarios specifically showed high exposure of producers to herbicides, with exposure levels ranging from 1.31 mg/kg bw/day to 1.67 mg/kg bw/day, well above the acceptable operator’s exposure levels (AOEL). These health risks could be significantly reduced if the required personal protective equipment is worn. But, recommended doses of pesticides should be reconsidered, because in some cases, applicators exposure remained high despite the protective equipment.

Carbon and Nitrogen Mineralisation of a Lixisol in South Sudan Zone of Burkina Faso

In today’s environment where agriculture needs to produce sustainably, local fertilizer resources must be encouraged to achieve multiple crop performance and environmental goals. The purpose of this study was to investigate the effects of combined inputs of biowaste and inorganic fertilisers on the mineralization of carbon and nitrogen of a Lixisol under continuous upland rice growing conditions. To this end, agronomic trials were set up in 2018 and 2019, using a Fisher randomized complete block design with 6 treatments and four replications at Farako-ba research station. The treatments were: T1 (Control), T2 (NPK + Urea), T3 (7500 kgha of Chicken droppings);T4 (7500 kg/ha of chicken droppings + 100 kg/ha of urea);T5 (7500 kg/ha of chicken droppings + 500 kg/ha of Burkina Phosphate);T6 (7500 kg/ha of chicken droppings + 500 kg/ha of Burkina Phosphate + 100 kg/ha of urea). Highest respirometry was observed in treatments T3, T4 and T6 and treatment T4 significantly increased the mineralization coefficient by 15% after 21 days of incubation. T4 and T6 resulted in increases in ammonium ion of 74.15% and 100%, respectively, compared to the control. Likewise, treatments T4 and T6 resulted in a significant increase in nitrate ion of 104.83 and 103.25%, respectively. Biowaste combined with inorganic fertilizers may have a capacity to improve the availability of leachate nutrients under upland rice conditions.

Soil Carbon Stocks Evolution in Organic Cotton-Based Cropping Systems in Southern and Northern Sudanese Agro-Ecological Zones of Burkina Faso

Variation of soil carbon stock in the cropping systems is an important indicator of their sustainability.The present study was conducted in 2015 and 2018 in seven organic cotton production areas distributed over the Southern and Northern Sudan agro-ecological zones in Burkina Faso.Soil samples were collected in 2015 as baseline and in 2018,after three years of cropping seasons,to determine the variations in carbon stocks in plots under organic farming systems.Surveys were also conducted to understand the fertilization practices implemented by producers during the same period.The results revealed that the recommended fertilization packages were not respected due to low production capacity and under using of organic manure.After three years of cropping in 2018,the deficit of organic restitution has led to a high decline of the soil carbon stocks.This decline was more severe in the 0-10 cm depth in some soils where the decrease in carbon stocks ranged from-4.6 t/ha to-5.5 t/ha.The correlation between soil types and their carbon stocks in the 0-10 cm soil layer was found to be significant(p<0.05)in the Northern Sudan agro-ecological zone with adjusted R2=74%and 54%in 2015 and 2018,respectively,and adjusted R2=56%(2015)and 44%(2018)in the Southern Sudan agro-ecological zone.After three years of organic cotton-based farming,a decrease in the correlation between soil types and their carbon content was observed in the majority of cases.These results show that the process of carbon storage in soil is more influenced by agricultural practices and agro-ecological conditions than by the soil type.

Microbial Properties of a Ferric Lixisol as Affected by Long Term Crop Management and Fertilization Regimes in Burkina Faso, West Africa

We used an ongoing long-term field trial established since 1960 in Burkina Faso, to study the microbial properties of a Ferric Lixisol under various crop management and fertilization regimes. Microbial respiration rate, microbial biomass carbon (MBC) and soil bacteria’s number were assessed in soil samples taken at 0 - 20 cm depth. The crop management were continuous cropping of sorghum (Sorghum bicolor L.) (S/S) and rotation between sorghum and cowpea (Vigna unguiculata L.) (S/C), while the fertilization regimes were: 1) Control (te);2) Low rate of mineral fertilizer (fm);3) Low rate of mineral fertilizer + sorghum straw restitution (fmr);4) Low rate of mineral fertilizer + low rate of manure (fmo);5) High rate of mineral fertilizer (FM);and vii) High rate of mineral fertilizer + high rate of manure (FMO). The manure is applied every second year. The results indicate that sorghum/cowpea rotation significantly increase MBC and bacteria number as compared to continuous sorghum cropping. MBC ranged from 335.5 to 54.85 μg C g−1 soil with S/S and from 457.5 to 86.6 μg C g−1 soil with S/C. Application of high level of manure and mineral fertilizer increase microbial respiration rate and MBC. The highest MBC was observed with FMO and the lowest with the control. In general, the metabolic quotient (qCO2) was negatively impacted by the fertilization and cowpea rotation. For S/S rotation, qCO2 of the control was 1.5 to 2 times that of the treatments with low mineral fertilizer (fmr, fmo and fm) and 3 times that of the high rate of fertilization (FM and FMO). With S/C rotation, qCO2 of the control was 2 times of that fmr, FM and FMO and 0.8 times that of fmo and fm. Soil bacteria in the fmr were 63.6 and 12.4 times the control in the S/S and S/C rotations, respectively. In sum, combined application of manure and mineral fertilizer with crop rotation is the best management practices to improve in sustainable way microbial activities in tropical soil.

Natural Enemies of Calidea panaethiopica (Heteroptera: Scutelleridae): An Insect Pest of Jatropha curcas L. in the South-Sudanian Zone of Burkina Faso

Jatropha curcas L. is a non-edible oleaginous plant of Euphorbiacea family. Its seeds provide oil for industrial use, and when grown as a biofuel, J. curcas can be used to restore degraded soil by improving their fertility and by controlling water and wind erosion. The plant also reduces CO2 emission by carbon sequestration. However, J. curcas is attacked by many insect pests including C. panaethiopica, a polyphagous heteroptera of the Scutelleridae family. Larvae and adults of the insect pest feed on J. curcas flowers, fruit, and seeds, thereby causing quantitative and qualitative losses. Despite the economic importance of this insect pest, there is little known about its potential natural enemies. A survey of the natural enemies of C. panaethiopica was carried out from 3rd June 2013 to 29th May 2014 on three J. curcas production sites in the South-Sudanian zone of Burkina Faso. Three Hymenopteran egg parasitoids all belonging to the Scelionidae family were found. These included Trissolcus basalis (Wollaston), Psixstriaticeps (Dodd), and Gryon sp. Several predator species belonging to the Araneae, Tarachodidae and Mantidae families were also found. The egg parasitism increased progressively between June and September 2013, reaching a peak (43%) in September 2013. The number of spiders and mantises was higher between July and August 2013. The highest numbers of natural enemies associated with the insect pest were recorded in J. curcas monoculture plantations.

Study of the Efficiency of the Aqueous Extract of Azadirachta indica’s Seeds and Deltamethrin on Jatropha curcas L. Insect Pests: Case of Calidea panaethiopica (Hemoptera: Scutelliridae) and Aphtona whitfieldi (Coleoptera: Chrysomelidae)

The efficiency of an aqueous extract of Azadirachta indica’s seeds and deltamethrin 12.5 EC was tested for the control of Calidea panaethiopica and Aphtona whitfieldi populations, two major insect pests of Jatropha curcas L. in Burkina Faso. This study was conducted in 2013 during the dry season and in 2014 during the raining season. In the laboratory, tests of toxicity by contact on paper blotter and by ingestion on organs of the plant and their repulsive effect on paper blotter were performed in vitro on the insect pests adults caught on J. curcasplantations as compared with controls. The aqueous excerpts of neem seeds were prepared at different lengths of steeping (12 h, 24 h and 48 h) and the deltamethrin 12.5 EC was diluted at different doses (4 ml, 8 ml and 16 ml/L). The results of this experiment showed the evidence of the efficiency of the doses 8 ml/L and 16 ml/L of deltamethrin 12.5 EC, and those of 24 h and 48 h for the excerpts of neem seeds. These efficient doses were evaluated in the field in 2013 and 2014. The highest decreases of C. panaethiopica (0.327) and of A. whitfieldi (0.501) populations were recorded with the 16 ml/L dose of deltamethrin in 2014 raining season. During the 2013 dry season, more insect pests were recorded (0.389 for C. panaethiopica and 0.679 for A. whitfieldi) with that dose. But these results were not significantly different from those of 8 ml/L. Regarding the A. indica extracts, the best decrease of populations in the 1st year (0.36 for C. panaethiopica and 1.278 for A. withfieldi) was recorded with the 48 h maceration. But in 2014 because of the effect of rainfalls that dose was less effective than that of 24 h maceration with 0.399 for C. panaethiopica and 1.208 for A. whitfieldi. The efficiency interval of the tested insecticides was two to three weeks in low or no rainfall conditions and one to two weeks in rainy season conditions.

On-Station and On-Farm Assessment of the Effects of Soil Cover on Conservation Agriculture Performances in Western Burkina Faso

Conservation agriculture (CA) is one option for dealing with such a challenge, but its main difficulty in West Africa is in maintaining permanent soil cover, particularly with crop residues, due to their preferential use for livestock fodder. The aim of our study was to determine the effect of crop residue mulching on the efficiency of cropping systems based on the principles of conservation agriculture. The experimental design was based on on-station experiments, intended to assess the specific effect of different levels of crop residue mulching on the biological and chemical soil fertility parameters, while in on-farm experiments we mainly assessed the ability of farmers to actually collect crop residues for soil cover and the associated effects on weeds and yields. The on-station experimental design was in fully randomized factorial blocks comprising five treatments and three replicates. The treatments compared the conventional system, tillage and cropping without mulching, and CA systems with 1 ton, 2 tons, and 4 tons of straw per hectare in plots of 10 m2. The effects of CA on the macrofauna, respiratory activity, and soil chemical parameters were evaluated in the 2014 and 2015 growing seasons. For the on-farm experiments, the conventional and CA practices of 15 farmers were compared to conventional practices in 2013 and 2014 in plots of 626 m2. The on-station results showed that the presence of crop residue mulching induced an increase in the density of termites. A significant release of carbon dioxide (CO2) in the CA treatments compared to the conventional treatment was also observed. For the chemical parameters (pH, N, P and K) were significantly and positively affected by mulch in the top 5 centimeters of soil. The on-farm experiments confirmed the difficulty of farmers in collecting enough biomass, with negative effects on grass cover leading to generally lower yields than conventional treatments. Other practices also affected the results, such as the maize sowing date, the gap between sowing and weeding, the gap between sowing and urea supply, the number of years of CA practices in the plot and, the gap between maize sowing and cowpea sowing. For the farmers having the human resources to collect enough crop residues for soil cover and follow the steps of the crop management sequences, it was possible to maintain yields compared to the conventional practice.

Alternative Host Plants of Calidea panaethiopica (Hemiptera: Scutelleridae) and Aphtona whitfieldi (Coleoptera: Chrysomelidae), Insect Pests of Jatropha curcas, South Burkina Faso

Jatropha curcas is subject to the attacks of many insect pests, including Calidea panaethiopica Kirkaldy 1909 (Hemiptera: Scutelleridae) whose larvae and adults feed on flowers, fruit and seeds of the shrub resulting in quantitative and qualitative losses;the shrub is also attacked by Aphthona whitfieldi Bryan (Coleoptera: Chrysomelidae) which feeds on the leaves causing complete defoliation in severe attack. Despite their economic importance, very little is known about the alternative host plants of these insect pests. The study of the ecology of these species is a pre-requisite for the development of appropriate control methods. The identification of alternative host plants of C. panaethiopica and A. whitfieldi was conducted from June 3rd 2013 to November 30th 2014 in the Sissili province, South Burkina Faso. During that period, four J. curcas’ plantations of six locations in the province were prospected for alternative host plants of the two insect pests. In each plantation, observations were done across a diagonal up to 500 m away from the plantation. Fallows in the vicinity of the J. curcas plantations were particularly examined. Potential host plants of the two insect pests were collected and bred in the laboratory in Léo where they were used to feed the insect pests. Only Jatropha gossypiifolia, a cousin of J. curcas, was found to be a common alternative host plant of both insect pests.

Alternative Host Plants of <i>Calidea panaethiopica</i>(Hemiptera: Scutelleridae) and <i>Aphtona whitfieldi</i>(Coleoptera: Chrysomelidae), Insect Pests of <i>Jatropha curcas</i>, South Burkina Faso

Jatropha curcas is subject to the attacks of many insect pests, including Calidea panaethiopica Kirkaldy 1909 (Hemiptera: Scutelleridae) whose larvae and adults feed on flowers, fruit and seeds of the shrub resulting in quantitative and qualitative losses;the shrub is also attacked by Aphthona whitfieldi Bryan (Coleoptera: Chrysomelidae) which feeds on the leaves causing complete defoliation in severe attack. Despite their economic importance, very little is known about the alternative host plants of these insect pests. The study of the ecology of these species is a pre-requisite for the development of appropriate control methods. The identification of alternative host plants of C. panaethiopica and A. whitfieldi was conducted from June 3rd 2013 to November 30th 2014 in the Sissili province, South Burkina Faso. During that period, four J. curcas’ plantations of six locations in the province were prospected for alternative host plants of the two insect pests. In each plantation, observations were done across a diagonal up to 500 m away from the plantation. Fallows in the vicinity of the J. curcas plantations were particularly examined. Potential host plants of the two insect pests were collected and bred in the laboratory in Léo where they were used to feed the insect pests. Only Jatropha gossypiifolia, a cousin of J. curcas, was found to be a common alternative host plant of both insect pests.

Study of the Efficiency of the Aqueous Extract of <i>Azadirachta indica</i>’s Seeds and Deltamethrin on <i>Jatropha curcas</i>L. Insect Pests: Case of <i>Calidea panaethiopica</i>(Hemoptera: Scutelliridae) and <i>Aphtona whitfieldi</i>(Coleoptera: Chrysomelidae)

The efficiency of an aqueous extract of Azadirachta indica’s seeds and deltamethrin 12.5 EC was tested for the control of Calidea panaethiopica and Aphtona whitfieldi populations, two major insect pests of Jatropha curcas L. in Burkina Faso. This study was conducted in 2013 during the dry season and in 2014 during the raining season. In the laboratory, tests of toxicity by contact on paper blotter and by ingestion on organs of the plant and their repulsive effect on paper blotter were performed in vitro on the insect pests adults caught on J. curcasplantations as compared with controls. The aqueous excerpts of neem seeds were prepared at different lengths of steeping (12 h, 24 h and 48 h) and the deltamethrin 12.5 EC was diluted at different doses (4 ml, 8 ml and 16 ml/L). The results of this experiment showed the evidence of the efficiency of the doses 8 ml/L and 16 ml/L of deltamethrin 12.5 EC, and those of 24 h and 48 h for the excerpts of neem seeds. These efficient doses were evaluated in the field in 2013 and 2014. The highest decreases of C. panaethiopica (0.327) and of A. whitfieldi (0.501) populations were recorded with the 16 ml/L dose of deltamethrin in 2014 raining season. During the 2013 dry season, more insect pests were recorded (0.389 for C. panaethiopica and 0.679 for A. whitfieldi) with that dose. But these results were not significantly different from those of 8 ml/L. Regarding the A. indica extracts, the best decrease of populations in the 1st year (0.36 for C. panaethiopica and 1.278 for A. withfieldi) was recorded with the 48 h maceration. But in 2014 because of the effect of rainfalls that dose was less effective than that of 24 h maceration with 0.399 for C. panaethiopica and 1.208 for A. whitfieldi. The efficiency interval of the tested insecticides was two to three weeks in low or no rainfall conditions and one to two weeks in rainy season conditions.