Mechanism(s) Underlying Interactions Between Cattle Manure and Mineral Fertilizer in a Maize Field Soil in Ghana

A 70-day laboratory incubation study was conducted to unravel the mechanism(s) underlying synergistic interactions between organic and inorganic nutrient inputs to the soil. Soil from a maize farmer's field at Kpongu in the Upper West Region of Ghana was amended with a factorial combination of 0, 50% and 100% levels of the recommended rates (RR) of inorganic fertilizer and cattle manure and incubated at room temperature in plastic cups. Deionized water was added to maintain soil moisture at 70% field capacity throughout the incubation period. Cups were covered with gas-permeable parafilm. Soil sampling was done at 7, 28, 42, 56 and 70 days after incubation. The soil was analyzed for available phosphorus, organic carbon, microbial biomass carbon, nitrates, ammonium, soil urease activity, iron, and copper at each sampling. The addition of 100% RR NPK + 50% RR manure often results in higher amounts of the measured parameters,synergistic interactions and supply of nutrients to the soil, with longer residual effects. While all the under-studied mechanisms (improved nutrient synchrony, priming effects, general fertility improvement fertility) contribute to synergistic interactions, the improved nutrient synchrony mechanism is the most prominent. Farmers can therefore manage the timing of the nutrient inputs well to capitalize on this mechanism for improved soil fertility.&nbsp

Determinants of fertilizer microdosing-induced yield increment of pearl millet on an acid sandy soil

Recent studies have reported the benefits of fertilizer microdosing in increasing crop yields in low input cropping systems. Little information is however available on the mechanisms underlying this effect. The objective of this study was therefore to explore the root-based mechanisms governing the growth enhancing phenomena of the fertilizer microdosing technology. A two-year experiment was conducted at the International Crops Research Institute for the Semi-Arid Tropics (ICRISAT), Research Station in Niger. Four treatments comprising (i) 2 g hill−1 of diammonuim phosphate (DAP), (ii) 6 g hill−1 of compound fertilizer NPK, (iii) broadcasting of 200 kg ha−1 of compound fertilizer NPK (recommended rate) and (iv) unfertilized control was arranged in a randomized complete block design with four replications. On average, fertilizer microdosing treatments (2-g DAP hill−1 and 6-g NPK hill−1) achieved 86% and 79% of the grain yields recorded from broadcasting of 200-kg NPK ha−1, respectively, in 2013 and 2014. The leaf area index and leaf chlorophyll content significantly increased with fertilizer microdosing at the early stage of millet growth. At the same stage, fertilizer microdosing enhanced the lateral root length density in the topsoil (0–20 cm) by 72% and 40% at respective lateral distances of 25 cm and 50 cm from the centre of the hill compared with broadcast of 200-kg NPK ha−1. Fertilizer microdosing did not significantly change soil pH in the root zone. It is concluded that the positive effect of fertilizer microdosing in increasing millet yield results from the better exploitation of soil nutrients due to early lateral roots proliferation within the topsoil

Fertilizer micro-dosing increases crop yield in the Sahelian low-input cropping system: A success with a shadow

Over the years, a scarcity of information on nutrient gains or losses has led to overemphasis being placed on crop yields and economic income as the direct benefits from fertilizer micro-dosing technology. There is increasing concern about the sustainability of this technology in smallholder Sahelian cropping systems. This study was designed in the 2013 and 2014 cropping seasons to establish nutrient balances under fertilizer micro-dosing technology and their implications on soil nutrient stocks. Two fertilizer micro-dosing treatments [2 g hill−1 of diammonium phosphate (DAP) and 6 g hill−1 of compound fertilizer Nitrogen-Phosphorus-Potassium (NPK) (15-15-15)] and three rates of manure (100 g hill−1, 200 g hill−1 and 300 g hill−1) and the relevant control treatments were arranged in a factorial experiment organized in a randomized complete block design with three replications. On average, millet (Pennisetum glaucum (L.) R.Br.) grain yield increased by 39 and 72% for the plots that received the fertilizer micro-dosing of 6 g NPK hill−1 and 2 g DAP hill−1, respectively, in comparison with the unfertilized control plots. The average partial nutrients balances for the two cropping seasons were −37 kg N ha−1yr−1, −1 kg P ha−1yr−1 and −34 kg K ha−1yr−1 in plots that received the application of 2 g DAP hill−1, and −31 kg N ha−1yr−1, −1 kg P ha−1yr−1 and −27 kg K ha−1yr−1 for 6 g NPK hill−1. The transfer of straw yields accounted for 66% N, 55% P and 89% K for removal. The average full nutrient balances for the two cropping seasons in fertilizer micro-dosing treatments were −47.8 kg N ha−1 yr−1, −6.8 kg P ha−1 yr−1 and −21.3 kg K ha−1 yr−1 which represent 7.8, 24.1 and 9.4% of N, P and K stocks, respectively. The nutrient stock to balance ratio (NSB) for N decreased from 13 to 11 and from 15 to 12 for the plots that received the application of 2 g DAP hill−1 and 6 g NPK hill−1, respectively. The average NSB for P did not exceed 5 for the same plots. It was concluded that fertilizer micro-dosing increases the risk of soil nutrient depletion in the Sahelian low-input cropping system. These results have important implications for developing an agro-ecological approach to addressing sustainable food production in the Sahelian smallholder cropping system

Willingness to pay for biofertilizers among grain legume farmers in northern Ghana

Open Access Journal; Published online: 27 April 2018Background: The call for use of improved Soil Fertility Management (SFM) technologies is a prerequisite to increase agricultural productivity among farmers. This study assessed farmers’ willingness to pay (WTP) for selected financially rewarding biofertilizer technologies/packages for legume production in northern Ghana. Primary data was elicited from 400 grain legume farmers selected from Northern and Upper West Regions of Ghana through a simple random sampling technique. The double bounded dichotomous choice (DBDC) format of contingent valuation approach was employed to elicit willingness to pay values and determinants of farmers WTP was evaluated using the maximum likelihood estimation procedure. Results: The results showed that about 60%, 25% and 46% of soya, cowpea and groundnuts farmers were willing to pay for the selected biofertilizers (Biofix, BR3267 and Legumefix respectively) at prices not exceeding GHC 14.00, GHC 28.00 and GHC 20.00 per 0.2kg of the respective biofertilizers. Legume farmers in Northern Region were however willing to pay higher for the three biofertilizer technologies as compared to their counterparts in Upper West Region. For 0.2 kg each of Biofix, BR3267 and Legumefix, farmers in Northern Region were willing to pay approximately GHC 17.00, GHC 12.00 and GHC 23.00 respectively whereas those in Upper West Region were willing to pay GHC 14.00, GHC 9.00 and GHC 11.00 for the same quantity of each biofertilizer. The study identified farming experience, FBO membership, awareness and previous use of biofertilizers as significant determinants of farmers’ willingness to pay for Biofertilizers. Conclusion: Comparatively, mean prices farmers are willing to pay for these three technologies are below ex-factory prices, hence subsidizing the cost of production of these biofertilizers in the initial stages would be relevant for improving farmers’ uptake of these fertilizers. Sustained awareness creation through periodic education and sensitization by using FBOs as leverage points is also highly recommended to improve farmers’ understanding of the concept of biofertilizer use

Nutrient release dynamics from decomposing organic materials and their mulching-effect on pearl millet yields in a low-input Sahelian cropping system

Organic material inputs for increased crop yields are insufficient in the Sahelian West Africa. There is a need for diversifying organic amendment sources for improved nutrient supply in low-input cropping system. The 2-year study aimed to (1) explore the rates of mass losses and nutrient release dynamics from Acacia tumida prunings (AT) and millet straw (MS) under field conditions, (2) assess termite’s contribution to the decomposition of AT and MS, and (3) ascertain the mulching-effect of these organic materials on pearl millet yields. The study was conducted in Niger using field experiment and litterbag methodology and the data modelled using single exponential decay equations. Under field conditions, mulching with AT and MS increased millet grain yield by 35 and 33%, respectively compared to control. The harvest index (HI) in 2014 increased by 21% compared to that obtained in 2013 with the highest HI being recorded for the AT mulched treatment. The results from litterbag experiment indicated a greater dry mass losses from MS decomposition in 2013 whereas relatively higher mass losses were recorded from AT decomposition in 2014. The differences in mass losses among the organic materials could be related to the interaction of soil moisture dynamics and termites’ population which are positively correlated with mass losses. The contribution of termites to the decomposition was estimated to be 36% for MS and 8% for AT. In 2013, at 126 days after litterbags placement, the amounts of N, P, and K released from MS were 16, 1, and 25 kg ha−1 of initial nutrient applied, respectively compared with the 22, 1, and 23 kg ha−1 recorded from AT treatment. During the same period in 2014, the total amounts of N, P and K released from MS were 15, 0.6, and 29 kg ha−1, respectively compared to the 32 kg ha−1 of N, 1 kg ha−1 of P, and 29 kg ha−1 of K released from the AT treatment. The intrinsic organic material quality could explain markedly the variation in nutrient released among the organic material. These results indicate that Acacia tumida prunings have a potential to provide nutrient through mineralization for enhanced crop yield in the Sahel

Fertilizer micro-dosing in West African low-input cereals cropping: Benefits, challenges and improvement strategies

Soil amendments are often unavailable in adequate quantities for increased crop production in smallholder cereal-based cropping systems in Africa. In order to increase crop yields and encourage farmers to apply inorganic fertilizers, fertilizer micro-dosing technology was developed. Fertilizer micro-dosing or “micro-fertilization” consists of the application of a small quantity of mineral fertilizer together with seeds of the target crop in the planting hole at sowing or 2-4 weeks after sowing. The objective of this paper is to review literature concerning crops responses to fertilizer micro-dosing in West Africa. The review also evaluates the benefits and challenges associated with nutrient management under fertilizer micro-dosing and supportive strategies for further improvement in the efficient use of limited nutrient sources of smallholder farmers were suggested. Recent scientific developments on fertilizer micro-dosing revealed that this technology has given promising results in respect of crop yields improvement, fertilizer use efficiency and economic returns. Other studies have, however, indicated that fertilizer micro-dosing increases the risk of soil nutrient imbalances due to low-input. For this reason, we suggest that fertilizer micro-dosing should be used in concert with organic amendments to optimize productivity of smallholder farmers in West Africa

Hill placement of manure and fertilizer micro-dosing improves yield and water use efficiency in the Sahelian low input millet-based cropping system

Inadequate nutrient supply and insufficient rainfall are the most important limiting factors for crop production in the Sahelian agro-ecological zones. Targeted technology application may help to improve the efficient use of limited nutrient and water resources. The objective of this study was to determine the optimal combination of fertilizer micro-dosing and manure application rates for improved millet yield and enhanced water use efficiency in low input millet-based cropping system. A two-year field experiment was conducted at a research station in Niger using a randomized complete block design with three replications. The treatments consisted of the factorial combination of: (i) two fertilizer micro-dosing options (20 kg ha−1 of diammonium phosphate (DAP) and 60 kg ha−1 of NPK corresponding to 2 g hill−1 of DAP and 6 g hill−1 of NPK, respectively), (ii) cattle manure at four application rates (0 kg ha−1, 1000 kg ha−1, 2000 kg ha−1, 3000 kg ha−1) and (iii) two methods of manure application (broadcasting and hill placement). Millet grain yields under fertilizer micro-dosing combined with manure was increased on average by 59%, 83% and 113% for 1000 kg ha−1, 2000 kg ha−1 and 3000 kg ha−1, respectively compared with fertilizer micro-dosing alone. Combined applications of manure and fertilizer micro-dosing increased water use efficiency significantly. Hill placement of manure increased total dry matter on average by 23% and water use efficiency by 35% relative to manure broadcasting. The total root length density was increased by 66% and 42% in hill placement of manure at 25 cm and 50 cm, respectively, from the hill centre compared with manure broadcast. These results indicate that millet production with the fertilizer micro-dosing technology can be improved further by hill-placement of manure. The combination of 2000 kg ha−1 of manure and 20 kg DAP ha−1 hill-placed were most promising for increasing millet yield and the efficient use of limited nutrients and water in Sahelian millet based systems. There is need for testing this technology further together with farmers to valuate its effectiveness