Fertility Investment Research Articles

Comparative Economic Analysis of Production, Resource Use Efficiency of Plant and Ratoon Sugarcane Cultivation in Gopalganj District of Bihar

The economics of planted and ratoon sugarcane cultivation have been studied in Gopalganj district of Bihar, by collecting primary data on various aspects of costs and returns, Benefit- cost ratio (BCR) and resource use efficiency. The study had shown that the value of BCR was higher for ratoon crop (3.26) than in planted crop (2.30). In all the situation, ratoon crops realized more profit from each rupees invested as compared to planted crop. The net return on operational cost realized per hectare were Rs. 114252 and Rs. 89304 is planted and ratoon condition. The almost resource input were found significant at 1% and 5% level of probability except human labour, fertilizers and plant protection chemicals used, these resources were not utilized efficiently resulting in low productivity of sugarcane. There is enough scope for investment in human labour, fertilizer and plant protection chemicals to increase productivity. Therefore, ratoon sugarcane was more remunerative and yield can be sustainable if induce the farmers to go for ratooning continuously and addressed a proper package of practices will be followed.

Agronomic and economic benefits of integrated nutrient management options for cowpea production

AbstractThe limitation of soil amendments and insufficient and irregular rainfall are the main factors accounting for the decline in crop yields in the Sahelian low-input cropping systems. This study explored the agronomic and economic responses of integrated use of millet glume-derived compost with synthetic fertilizer in cowpea-based cropping system. A two-year field experiment was laid out as factorial design arranged in randomized complete blocks with three rates of compost (0, 4000, and 8000 kg ha−1) and three rates of recommended synthetic fertilizer (0, 50, and 100%). Cowpea grain yield increased markedly with combined application of compost and synthetic fertilizer. The combined use of compost applied at 8000 kg ha−1 and 50% of the recommended rate of synthetic fertilizer increased cowpea grain yield by 51% compared to the application of 100% of the recommended rate of synthetic fertilizer. The rainwater use efficiency (RaUE) increased by 52 and 49% with the combined application of compost at 8000 kg ha−1 along with 50% of the recommended rate of synthetic fertilizer when compared to the application of 100% of the recommended rate of synthetic fertilizer in 2013 and 2014, respectively. All treatments induced a positive net income, and the highest value/cost ratio was achieved with combined application of compost and synthetic fertilizer. This study highlights the possibility of improving cowpea productivity through combined use of composted locally available organic input with half of the recommended rate of synthetic fertilizer. This combination would reduce the investment in mineral fertilizer currently made by smallholder farmers in the Sahelian low-input cowpea cropping system and reduce environmental pollution resulting from the current practice of burning the millet glume.

Soil‐test biological activity with the flush of CO2: VI. Economics of optimized nitrogen inputs for corn

AbstractStandard N fertilizer rates for corn (Zea mays L.) production are often based on yield goal and a simplified N factor. Unfortunately, simplified systems generally ignore management history that affects soil health condition. We analyzed economic return to N fertilizer investment using a soil‐test biological activity (STBA)‐based approach compared with current approaches in the United States, and specifically in North Carolina (NC) and Virginia (VA). The STBA‐based approach addressed management history on 99 fields through cumulative effects on biological activity as an indicator of soil health. Economically optimum N fertilizer rate was determined for each field from replicated, small‐plot trials with four N rates applied to corn at sidedress and using four levels of cost‐to‐value threshold (CVT; i.e., 5, 10, 15, and 20 kg grain kg−1 N). Economic return was often greater using the STBA‐based method compared with current recommendation systems (US$4.10 ± 4.96 ha−1, $23.63 ± 5.30 ha−1, $49.36 ± 5.63 ha−1, and $83.22 ± 6.81 ha−1 with low, medium, high, and very high CVTs, respectively; mean ± standard error). Greater STBA led to greater economic return (i.e., $0.03 ha−1 [p = .58], $0.23 ha−1 [p < .001], $0.28 ha−1 [p < .001], and $0.33 ha−1 [p < .001] for every unit increase in STBA [mg kg−1] at low, medium, high, and very high CVTs, respectively). Farmers can increase profit by adopting soil‐health building practices and adjusting N fertilizer inputs in their nutrient management plan in response to conserved nutrient cycling in the biologically active organic fraction.

Impact of Nitrogen Fertilizer on Yield and Associated Revenues in No-tillage Pumpkin

The use of no tillage (NT) integrated with cover cropping is a management practice that is becoming more popular with commercial ‘jack-o-lantern’ pumpkin (Cucurbita pepo) growers in the eastern and midwestern United States, although little is known about nitrogen (N) fertilizer requirements for this production system. A field study was established at the Southern Illinois University Horticulture Research Center in Carbondale to evaluate the yield response of pumpkin and associated revenues to N fertilization in a NT production system after wheat (Triticum aestivum) harvest. Nitrogen application rate affected pumpkin leaf chlorophyll content, and resulting yields and revenues. At all sampling dates, pumpkin fertilized with 224 kg·ha−1 N had the greatest leaf chlorophyll content. Quadratic relationships best described pumpkin fruit size and diameter increase with N rates from 0 to 224 kg·ha−1. Furthermore, pumpkin fruit number and weight per hectare also increased in a quadratic manner, as N application rates increased from 0 to 224 kg·ha−1. The application of 168 kg·ha−1 N also provided high yields and large fruit sizes, although quadratic models indicated that maximum net revenues for NT pumpkins were achieved with 224 kg·ha−1 N. Growers applying 224 kg·ha−1 N would increase net revenues by ≈54%, 52%, and 51% at pumpkin fruit price points of $0.33, $0.44, $0.55 per kg, respectively, compared with 0 kg·ha−1 N fertilization. An additional 123 kg·ha−1 N from fertilizer was required for NT pumpkin production after wheat harvest in fields with high amounts of cereal straw residues on the soil surface compared with the 101 kg·ha−1 N recommended for conventional tillage systems with no cover crop residues. This study suggests that N fertilizer investments will provide significant monetary returns in NT pumpkin systems. However, the 168 kg·ha−1 N rate provided the highest return on fertilizer investment at all pumpkin pricing points compared with all other N rates evaluated. Additionally, pumpkins grown in NT systems using a winter grain crop that is ended at flowering should require similar N amounts, because little N is used during heading and grain ripening. Although growers often look for ways to reduce input costs in vegetable production systems, N fertilization is clearly an important investment that provides increased yields and revenues in NT pumpkins. The results of this study should provide additional information to establish N fertilizer recommendations for NT pumpkin production.

Improving access to savings through mobile money: Experimental evidence from African smallholder farmers

Abstract Investment in improved agricultural inputs is infrequent for smallholder farmers in Africa. One barrier may be limited access to formal savings. This is the first study to use a randomized controlled trial to evaluate the impact of using mobile money as a tool to promote agricultural investment. For this purpose, we designed and conducted a field experiment with a sample of smallholder farmers in rural Mozambique. This sample included a set of primary farmers and their closest farming friends. We work with two cross-randomized interventions. The first treatment gave access to a remunerated mobile savings account. The second treatment targeted closest farming friends and gave them access to the exact same interventions as their primary farmer counterparts. We find that the remunerated mobile savings account raised mobile savings, but only while interest was being paid. It also increased agricultural investment in fertilizer, although there was no change in investment in other complementary inputs that were not directly targeted by the intervention, unlike fertilizer. These results suggest that fertilizer salience in the remunerated savings treatment may have been important to focus farmers’ (limited) attention on saving some of their harvest proceeds, rather than farmers being financially constrained by a lack of alternative ways to save. Our results also suggest that the network intervention where farming friends had access to non-remunerated mobile money accounts decreased incentives to save and invest in agricultural inputs, likely due to network free-riding because of lower transfer costs within the network. Overall this research shows that tailored mobile money products can be used effectively to improve modern agricultural technology adoption in countries with very low agricultural productivity like Mozambique.

Effect of nutrient management approaches on seed yield and nutrient uptake of soybean-sorghum based cropping system

The improvement in seed yield characters was the manifestation of improved growth characters as a result of higher uptake of nutrients caused by balanced supply of nutrients in this regard soil test based nutrient management approaches aims provide a scientific basis for balanced fertilization to obtain more yield per unit of fertilizer investment. An experiment was conducted during kharif and rabi seasons of 2017-18 and 2018-19 at Agricultural Research Station, Janwada, Bidar district, which comes under the jurisdiction of University of Agricultural Sciences, Raichur, to study the soil test based nutrient management approaches on seed yield and nutrient uptake of soybean-sorghum cropping sequence. Pooled results indicate that maximum seed yield (27.82q ha-1) was recorded with application of nutrients as per SSNM approach for targeted yield of 30q ha-1+25kg FeSO4 5H2O ha-1 in soybean. Similarly maximum sorghum grain yield (1210kg ha-1) was recorded with the residual effect of nutrients through SSNM approach for targeted yield of 30q ha-1 +25kg FeSO4 5H2O ha-1 and higher uptake of nutrients (seed +haulm) viz., nitrogen (231.99kg ha-1), phosphorus (17.17kg ha-1), potassium (90.04kg ha-1) sulphur (55.82kg ha-1), zinc (159.36g ha-1), iron (3035.2g ha-1), and), boron (75.88g ha-1) by soybean. Similarly higher uptake of nutrients (grain +stover) viz., nitrogen (22.83kg ha-1), phosphorus (9.64kg ha-1), potassium (29.43kg ha-1), sulphur (2.68kg ha-1), zinc (49.70g ha-1),), iron (121.04g ha-1), and), boron (20.98g ha-1) by sorghum was recorded with residual effect of nutrients through SSNM approach targeted yield of 30q ha-1 +25kg FeSO4 5H2O ha-1 as compared to absolute control, RDF, and other soil test methods.

Compostagem e vermicompostagem como alternativa para tratamento e de destinação de resíduos orgânicos

Os solos de regiões semiáridas apresentam naturalmente uma baixa fertilidade, dificultando o crescimento e a produtividade das plantas, aumentando os custos de produção, devido aos investimentos com fertilizantes e defensivos agrícolas. Além disso, globalmente existe grande desperdício de alimentos. Diante deste cenário, objetivou-se com o presente trabalho avaliar o reaproveitamento dos resíduos orgânicos para a produção de um composto orgânico por meio de compostagem, seguido de vermicompostagem. O experimento foi realizado em duas etapas (compostagem seguida de vermicompostagem), no Instituto Federal de Educação Ciência e Tecnologia do Ceará Campus Maracanaú. Foram utilizados resíduos orgânicos alimentares, provenientes da Central de Abastecimento do Ceará, esterco bovino e folhas secas. Aos 51 dias após o início da compostagem, o composto foi colocado em um depósito com capacidade de 310 L e foram adicionadas 100 minhocas californianas adultas (Eisenia foetida), iniciando assim o processo de vermicompostagem. Concluiu-se que é possível utilizar os resíduos alimentares para a produção de composto orgânico fertilizante. A compostagem seguida de vermicompostagem mostrou-se viável e de fácil aplicação. A vermicompostagem diminuiu a granulometria do composto e melhorou a qualidade nutricional do material, aumentando os teores de fósforo, cálcio, zinco, cobre e ferro.

Bombs and Babies: Terrorism Increases Fertility in Nigeria

This paper studies the association between exposure to Boko Haram's attacks and households' fertility choices in Nigeria. In our model, parents decide not only how many children they want to have, but also how much they want to invest in them. The model's predictions suggest that households exposed to terrorism increase their number of children as a way to insure against future unexpected shocks and reduce investment in their offspring. We test the predictions of the model using geolocalized panel data linked to information on terrorist attacks that occurred in the region. Consistent with the theory, terrorism is found to increase fertility (proxied by the number of surviving children per household) and decrease parental investment (proxied by child malnutrition). The first association is robust to the use of difference-in-differences and instrumental variables models – and therefore can be given a causal interpretation – but the second is not.

Improving Access to Savings Through Mobile Money: Experimental Evidence from African Smallholder Farmers

Investment in improved agricultural inputs is infrequent for smallholder farmers in Africa. One barrier may be limited access to formal savings. This is the first study to use a randomized controlled trial to evaluate the impact of using mobile money as a tool to promote agricultural investment. For this purpose, we designed and conducted a field experiment with a sample of smallholder farmers in rural Mozambique. This sample included a set of primary farmers and their closest farming friends. We work with two cross-randomized interventions. The first treatment gave access to a remunerated mobile savings account. The second treatment targeted closest farming friends and gave them access to the exact same interventions as their primary farmer counterparts. We find that the remunerated mobile savings account raised mobile savings, but only while interest was being paid. It also increased agricultural investment in fertilizer, although there was no change in investment in other complementary inputs that were not directly targeted by the intervention, unlike fertilizer. These results suggest that fertilizer salience in the remunerated savings treatment may have been important to focus farmers' (limited) attention on saving some of their harvest proceeds, rather than farmers being financially constrained by a lack of alternative ways to save. Our results also suggest that the network intervention where farming friends had access to non-remunerated mobile money accounts decreased incentives to save and invest in agricultural inputs, likely due to network free-riding because of lower transfer costs within the network. Overall this research shows that tailored mobile money products can be used effectively to improve modern agricultural technology adoption in countries with very low agricultural productivity like Mozambique.

Perceptions, Risk Attitude and Organic Fertilizer Investment: Evidence from Rice and Banana Farmers in Guangxi, China

Overuse of chemical fertilizer has led to severe land degradation and environmental pollution in China. Switching to organic fertilizer may improve soil quality and reduce pollution, which is meaningful to the sustainable development of Chinese agriculture. This study examines how farmers’ perceptions and risk preference affect their organic fertilizer investment using a representative rural household survey from Guangxi, a major agricultural region in China. Tobit and double-hurdle models are used to empirically test their impacts on organic fertilizer adoption and investment. An ordinary least squares model is used to regress chemical fertilizer use on the same set of explanatory variables to compare and contrast farmers’ different fertilizer investment behaviors. It is found that both organic fertilizer perceptions and risk attitude significantly affect organic fertilizer investment. Perceived yield-increasing and quality-improving effects encourage organic fertilizer investment, while perceived cost increases discourage it. Moreover, risk-averse farmers are more likely to invest in organic fertilizers. Most of the perceptions affecting organic fertilizer investment have an opposite impact on chemical fertilizer investment, which suggests substitutability between organic and chemical fertilizer. Interventions that aim to improve farmers’ perceptions of organic fertilizer and illustrate its risk-reduction effect could be effective in promoting organic fertilizer use, which can help achieve China’s sustainable development of agriculture.

Formalization without certification? Experimental evidence on property rights and investment

We present evidence from the first large-scale randomized-controlled trial of a land formalization program. We examine the link between land demarcation and investment in rural Benin in light of a model of agricultural production under insecure tenure. The demarcation process involved communities in the mapping and attribution of land rights; cornerstones marked parcel boundaries and offered lasting landmarks. The tenure security improvement through demarcation induces a 23 to 43 percent shift toward long-term investment on treated parcels. We explore gender and parcel location as relevant dimensions of heterogeneity. We find that female-managed landholdings in treated villages are more likely to be left fallow—an important soil fertility investment. Women respond to an exogenous tenure security change by shifting investment away from relatively secure, demarcated land and toward less secure land outside the village to guard those parcels.

Refining Fertilizer Rate Recommendation for Maize Production Systems in Assosa, North Western Ethiopia

Maize growers need balanced crop nutrition to maximize its yield potential and get the most out of their fertilizer investment. In practice, this requires making all of the required nutrients available to the maize crop by the right amount or rate. The objectives of this study was to determine optimum N, P, K and S response curve under balanced fertilization and to establish economic mixes blended fertilizers and determine soil, crop specific optimum N, P, K and S fertilizers rates for maize crop grown in Assosa areas. The experiment was conducted using randomized complete block design (RCBD) with three replications consisting of a total of 8 treatments for N, P, K and 10 treatments for S. Therefore; the result revised that the N level was highly significant (P<0.05) on grain yield. The highest grain yield (7292.5 kg ha-1) was obtained at the lowest nitrogen rate with balanced fertilizer of 46 kg N ha-1+PKSZnB while significantly the lowest grain yield (3298.6 kg ha-1) was records from control. The application of 69 kg ha-1 P resulted in grain yield increases, aboveground biomass yield was also affected in the same amount of P with balanced fertilizers having increased biomass yield with P application. Even if the ANOVA results shows significant difference on that of treated with K fertilizer, there was slight variation within treatments except the highest rates of K fertilizer. Across the S rate studies, all S rates with balanced fertilizers had a statistically significant yield increment from the control and Recommended NP. From the across-treatment yield increase, treatment 10 Kg S ha-1+NPKZnB gives maximum yield (6717.7 kg ha-1). Analyzed across S rate, the economic optimum S rate was also 10 Kg S ha-1 for the clay textured soils of Assosa.

Agricultural Cooperatives and Investment in Organic Soil Amendments and Chemical Fertilizer in China

AbstractIn this article, we develop a dynamic model to show how membership in agricultural cooperatives influences smallholder farmers' decisions to invest in organic soil amendments and chemical fertilizer. The model considers management decisions of heterogonous producers within an intertemporal framework, with the decision to join the cooperative assumed to be endogenous. Farm‐level data of apple farmers from three provinces in China are used to estimate the impact of cooperative membership on investment in organic soil amendments and chemical fertilizer. A recursive bivariate probit model that accounts for potential endogeneity of cooperative membership and selection bias is employed in the empirical analysis. The empirical results show that cooperative membership exerts a positive and statistically significant impact on the likelihood of investing in organic soil amendments. The findings also reveal that tenure security, human capital, farm size, and access to credit positively and significantly influence the probability of a farmer joining a cooperative and the likelihood of investing in soil quality measures.

Cultivars of canola respond similarly to applied nitrogen in n-deficient soils of south Western Australia

ABSTRACTSix cultivars of canola (Brassica napus L.) were grown with six levels of applied nitrogen (N) fertilizer (urea 46% N) at six locations in south Western Australia (SWA) during 2010 and 2011. The aim of the experiment was to determine if the seed yield (SY) increase (response) of the canola and associated herbicide technologies were different to applied N. Open pollinated (OP) and hybrid cultivars of associated herbicide technologies (Triazine Tolerant, TT; Roundup Ready, RR; Clearfield, CL) were used. Varieties had large SY differences with no N applied. Generally, RR hybrid of 2011 tended to have the highest SY, except for Katanning 2011 where several varieties obtained the same SY. The average amount of N required for 90% of the maximum SY was 113 kg N ha−1 and economic breakeven N rates were less than or equal to 100 kg applied N ha−1. The average rate of return on investment in fertilizer N was $1.60.In four out of six experiments RR hybrids had the highest oil concentration with no applied N. N decreased the oil concentration in all canola types, except at Gibson 2010. At Gibson in 2010, N application increased the oil concentration to about 100 kg N ha−1 with further additions of N decreasing the oil concentration. There was a linear relationship where N application decreased the oil concentration and increased protein concentration of the seed. In this study, the summation of oil percentage and protein concentration in the seed was on average 65%, with RR hybrids producing 67%.In most aspects, RR hybrids outperformed RR, OP and other canola types; however, hybrid TT and hybrid CL canola did not consistently outperform their OP counterpart. We suggest that current N fertilizer recommendation models are useful for all canola types currently grown in SWA; however, adjustments should be made to take into account the higher SY and oil concentration potential of RR hybrids compared to TT canola at every rate of applied N.

Evaluation of Soybean Cultivars of Contrasting Cycles according to the Level of Investment in Fertilization

The objective of the present study was to characterize the duration of the phenological stages, the agronomic characteristics and grain yield in soybean cultivars with contrasting cycles and indeterminate growth type, submitted to different fertilization investment environments under no-tillage system in the central region of Minas Gerais. The work was conducted under field conditions, in an experimental area of Embrapa Maize and Sorghum, in Sete Lagoas, MG, in the harvest of 2015/2016. Ten soybean cultivars with different relative maturity groups (RMG) were studied, representing almost all RMG materials currently sown in Minas Gerais, in two environments with different levels of fertilizer investment. The variables were submitted to analysis of joint variance, in order to verify the existence of interaction between cultivars and investment in fertilization environments. Fertilizer investment levels influence grain yield of soybean cultivars of contrasting cycles. The higher height of the soybean plants implies higher lodging and lower grain yield. This situation is aggravated by the greater investment in fertilization. The difference between the cycles of the cultivars is in the duration of the vegetative stages, being greater in the later cultivars.

Fertilizers, hybrids, and the sustainable intensification of maize systems in the rainfed mid-hills of Nepal

Abstract In the rainfed mid-hill region of Nepal, most fields receive 2–3 t ha−1 of organic compost application every year. Despite efficient recovery and use of organics in the mixed crop-animal systems that predominant in the mid-hills, depleted soil fertility is widely understood to be a significant constraint to crop productivity, with most farmers achieving maize grain yields below 2 t ha−1. Increased use of fertilizer may arrest and even reverse long-term soil quality degradation, but few farmers in the mid-hills use them at present and existing recommendations are insufficiently responsive to site, varietal, and management factors that influence the productivity and profitability of increased fertilizer use. Moreover, policy makers and development practitioners often hold the perception that returns to fertilizer use in the mid-hills are too low to merit investment. In this study, on-farm experiments were conducted at 16 sites in the Palpa district, Nepal to assess the responsiveness of a maize hybrid (DKC 9081) and an ‘improved’ open-pollinated maize variety (‘OPV’, Manakamana-3) to four nitrogen (N) rates, i.e., 0, 60, 120 and 180 kg ha−1, with each N rate response evaluated at 30:30 and 60:60 kg ha−1 rates of phosphorus (P2O5) and potassium (K2O), respectively. With sound agronomy and high rates of fertilizer (180:60:60 kg N:P2O5:K2O ha−1), grain yields observed in the field experiments exceeded 8 t ha−1 with hybrids and 6 t ha−1 with OPV. Yield levels were lower for OPV than hybrid at every level of applied N, but both genotypes responded linearly to N with partial factor productivity for N (PFPN) ranging from 14 to 19 for OPV versus 26–30 for hybrid, with improved N efficiencies obtained when P and K rates were significantly higher. Averaged across phosphorus (P) and potassium (K) levels, a $ 1 incremental investment in fertilizer increased the gross margin (GM) by $ 1.70 ha−1 in OPV and by $ 1.83 ha−1 in the hybrid. For the full response of N, requires higher rate of P2O5:K2O and vice-versa and full response to P2O5:K2O does not occur if N is absent. These results suggest that, i) degraded soils in the mid-hills of Nepal respond favorably to macronutrient fertilizers – even at high rates, ii) balanced fertilization is necessary to optimize returns on investments in N but must be weighed against additional costs, iii) OPVs benefit from investments in fertilizer, albeit at a PFPN that is 36–47% lower than for hybrids, and, consequently iv) hybrids are an effective mechanism for achieving a higher return on fertilizer investments, even when modest rates are applied. To extend these findings across years and sites in the mid-hills, crop growth simulations using the CERES-maize model (DSSAT) were conducted for 11 districts with historical weather and representative soils data. Average simulated (hybrid) maize yields with high fertilizer rate (180:60:60 kg N:P2O5:K2O ha−1) ranged from 3.9 t ha−1 to 7.5 t ha−1 across districts, indicating a high disparity in attainable yield potential. By using these values to estimate district-specific attainable yield targets, recommended N fertilizer rates vary between 65 and 208 kg N ha−1, highlighting the importance of developing domain-specific recommendations. Simulations also suggest the potential utility of using weather forecasts in tandem with site and planting date information to adjust fertilizer recommendations on a seasonal basis.

Breeding patterns of three species of Armadillidium (Isopoda, Oniscidea) from Tunisia

The breeding patterns ofArmadillidiumsp. from Ichkeul,A. sulcatumfrom El Feija andA. tunisiensefrom El Jerissa were studied based on a rearing during 12 months under natural conditions in the laboratory. These populations exhibited a seasonal reproduction. With the exception ofA. tunisiense, virgin and isolated females ofA. sulcatumandArmadillidiumsp. realized a spontaneous vitellogenesis, followed by a parturial moult. The onset of the female’s reproduction ofArmadillidiumsp. andA. sulcatumwas accelerated by male presence. The presence of males also extended their reproductive duration. During the breeding season, mated females of the three populations ofArmadillidiumexhibited a variation in the succession of performed moults and were iteroparous. The mean weight of a population seemed to be the most important determining factor in controlling sexual differentiation and maturity, the gestation period, mean fertility, reproductive allocation, and parental investment.

Nutrient Management Strategies on Heterogeneously Fertile Granitic‐Derived Soils in Subhumid Zimbabwe

Maize (Zea mays L.) is the staple food in southern Africa, but low soil fertility and lack of effective fertilization strategies for variable soil conditions hamper efficient use of nutrient resources. The objective of this study was to establish the influence of soil fertility heterogeneity on maize yield response to manure, liming, and inorganic fertilizers. Three sites, selected to represent three soil fertility domains based on soil organic carbon (SOC) between 3.5 to 8.9 g SOC kg−1 soil, were used during two cropping seasons. Nitrogen, P, K, and S were applied alone (NPKS) or in combinations involving lime, cattle manure, and micronutrients. Grain and stover were analyzed for nutrient uptake, and agronomic efficiencies were computed for N and P. Across sites, maize grain yields increased with increasing SOC. In Year 2, lime was the most important component for increasing maize yields in low SOC soil. For the medium and high SOC soils, treatments with NPKS + manure resulted in the best efficiencies. Although soil pH was low in these fields as well, lime which was applied only in Year 1, did not improve yields either year. Maize yields and nutrient uptake were strongly affected by SOC content, with yields for a site with 3.5 g SOC kg−1 soil significantly lower than the two sites that had &gt;5.3 g SOC kg−1soil. We conclude that farmers must strategically target their limited nutrients resources to fields that are not yet degraded and maintain soil fertility to guarantee returns to fertilizer investments.

Maize productivity and nutrient and water use efficiencies across soil fertility domains on smallholder farms in Zimbabwe

Strategic targeting of scarce nutrient resources by smallholder farmers on different field types has remained poor partly due to knowledge limitations, resulting in inefficient use of the resources. We sought to establish efficient strategies for use of nutrient resources so as to narrow the yield gap in maize production on heterogeneous light-textured soils under rain-fed conditions in Eastern Zimbabwe. A nutrient omission study was implemented during two cropping seasons, across six on-farm sites with soil organic carbon (SOC) ranging from 3.5 to 8.9gkg−1, and clay content between 4 and 19%. Treatments used were: (i) a zero fertilizer control, (ii) NK, (iii) NPS, (iv) PKS, and (v) NPKS. Rainfall water productivity, RWP, (kggrainmm−1) was used as a proxy for water use efficiency for the different nutrient combinations. During both seasons, only 70kgha−1 N could be applied across all sites as prolonged mid-season droughts forced withholding of the second N topdressing targeted at maize anthesis. Maize productivity was influenced by both nutrient management and initial soil fertility. During the first season, maize yields across sites ranged from 0.25 to 0.84tha−1 for the control and 2.05–3.75tha−1 for the NPKS treatment that represented attainable yields. The corresponding RWP were 0.38–1.13kggrainmm−1 for the control and 3.15–7.66kggrainmm−1 for the NPKS treatment. For the second season, maize yields for the control ranged from 0.2 to 1.2tha−1, while those for the NPKS treatments ranged from 2.4 to 3.60tha−1. Across sites, response to N ranged 1.2–2.35tha−1, response to P ranged 0.71–2.10tha−1 and response to K ranged 0.08–0.30tha−1, indicating little response to K. Overall, balanced nutrient management has an overriding effect on maize grain and water productivity, but only for soils with SOC>4gkg−1 soil. Nitrogen and P remain the most limiting nutrients, in contrast, addition of K did not enhance grain yield, nor did it influence response to N or P. Variable N application strategies must be an integral component of farmer management if losses related to fertilizer investment are to be minimised under the risky rain-fed crop production systems.

Determinants and Profitability of Rice production in Cyabayaga Watershed, Eastern Province, Rwanda

The aim of this study was to analyze the determinants of rice production and its financial profitability in the watershed of Cyabayaga, Eastern Province of Rwanda. The study was composed of a stratified sample of 46 rice growers and members of CODERVAM cooperative operating in the same watershed. The Cobb-Douglas production function was adapted and estimated to indicate individual effects of labor, land, and capital on rice production. In addition, a Cost-Benefit Analysis (CBA) approach was opted to compute the financial profitability of rice growing in the study area. Results from the analysis substantiate that cultivated area (land) and labour had significant (5% significance level) contribution to rice yield. However, capital investment in form of inputs ( seeds and fertilizers) was not statistically significant even at 15 % significance level, indicating lower contribution to production of rice in the study area, all else equal. Some farmers reported insufficient income to invest in rice production thus making the overall contribution of the investment factor insignificant for this case study. Findings from the Cost Benefit Analysis (CBA) indicated that only one category of farmers, among the three sampled, had positive Net Present Value (NPV). The implication for negative NPVs is that rice growers do not invest appropriately, leading to lower returns. The two analytical approaches led to a similar conclusion that the capital factor represented by investments in seeds and fertilizers does not explain significantly the rice production observed in the Cyabayaga Watershed. It is recommended to support these farmers to have access to inputs and agricultural trainings. These constitute the major area of their investments and constraints for improved and well sustained rice production in the study area.Key words: Financial profitability, Rice production, Cyabayaga Watershed, Rwanda