Soil Fertility Replenishment Research Articles

Evaluating the impacts of area closure on soil properties in south central highland of Ethiopia

Soil degradation affects its quality and productivity of the land. To control soil degradation, various soil and water conservation (SWC) measures, including area closure are implemented. Understanding the impacts of SWC measures could support planning and implementation of land management practices. This study aimed to investigate impacts of area closure on soil properties in south central highland of Ethiopia. To acquire the necessary data, we conducted interviews with 80 households. Furthermore, nine years old area closure with physical soil and water conservation (AC-SWC), open grazing with physical SWC (OG-SWC), and open grazing without physical SWC (OG) were identified and each divided into upper, middle, and lower slope positions. In each slope position, 3 sample plots were established at 25–50 m intervals. A total of 27 composite samples and other 27 core samples for bulk density (3 treatments∗3 slope position∗3 replications) were collected and analyzed for soil properties. The data were analyzed using descriptive statistics and one-way ANOVA. The results showed that about 98 % of the respondents perceived that area closure would be an effective way to restore degraded land. Majority of the farmers (86 %) believed that area closure could reduce soil erosion and replenish soil fertility and thus, is beneficial in improving land productivity. Soil test results revealed that AC-SWC had significantly greater (P < 0.05) clay fractions, pH, available potassium, and available phosphorus than OG-SWC and OG. Variations of soil organic carbon (SOC) and total nitrogen (TN) were more pronounced. The SOC in AC-SWC was 83 % and 314 % greater than OG-SWC and OG, respectively. In the AC-SWC, TN was three and seven times higher than that of OG-SWC and OG, respectively. This could be due to vegetation restoration that reduces erosion, and enhances organic matter, moisture, and nutrient. The SOC, TN, pH, available potassium, and clay were significantly greater (P < 0.05) at lower slope position than upper in all forms of land management, which could be due to deposition at downslope. About 12 % and 11 % variations of clay fractions and SOC were, respectively, observed in between upper and lower slope positions at AC-SWC, but they varied by 25 % and 57 %, respectively, in OG. These imply area closure has had a beneficial effect on soil properties even on sloping land. AC-SWC is an important option to integrate in land management for rehabilitation of degraded soil.

Transcriptomes of soybean roots and nodules inoculated with Sinorhizobium fredii with NopP and NopI variants.

The major crop, soybean, forms root nodules with symbiotic rhizobia, providing energy and carbon to the bacteria in exchange for bioavailable nitrogen. The relationship is host-specific and highly host-regulated to maximize energy efficiency. Symbiotic nitrogen fixation (SNF) is greener than synthetic fertilizer for replenishing soil fertility, contributing to yield increase. Nodulation Outer Protein P (NopP) and NopI of the type 3 secretion system (T3SS) of the rhizobium determine host specificity. Sinorhizobium fredii CCBAU25509 (R2) and CCBAU45436 (R4) have different NopP and NopI variants, affecting their respective symbiotic compatibilities with the cultivated soybean C08 and the wild soybean W05. Swapping the NopP variants between R2 and R4 has been shown to switch their compatibility with C08 with the rj2/Rfg1 genotype. To understand the effects of Nops on host compatibility, analyses on the transcriptomic data of W05 roots and nodules inoculated with S. fredii strains containing Nop variants uncovered many differentially expressed genes related to nodulation and nodule functions, providing important information on the effects of Nops on hosts and nodules.

Contribution of Banana Production on Household Income Generation Among Smallholder Farmers in Kitagata Town Council, Sheema District

The study was about contribution of banana production on house hold income generation among Smallholder farmers in Kitagata town council, Sheema District. The specific objectives included to; examine the socio-economic characteristics of smallholder banana farmers, establish innovative strategies to improve banana production and income among smallholder banana farmers and identify the factors affecting banana production and income among smallholder banana farmers. The study adopted a cross-sectional survey that applied both quantitative and qualitative approaches for data collection. Data was captured from a sample of 302 respondents using both questionnaire and interviews. Data was analyzed using SPSS software version 22.0 to generate both descriptive and inferential statistics. The study concluded that there were socio-economic characteristics of farmers which also affected banana production. Such characteristics included; age, marital status, level of education land size and gender. The study also concluded that there were innovative strategies to improve banana production and income among smallholder banana farmers in Kitagata town council, Sheema district. These included; Integrated Pest Management, use of hybrid varieties, Irrigation, mulching, climate-Smart Agriculture through use of drought resistant varieties, agro-forestry, use of fertilizer application and organic manure to replenish soil fertility. The study finally concluded that there were factors affecting banana production and income among smallholder banana farmers. Such as; access to extension and advisory services which had a significant effect on production and smallholder farmer’s income at (p=.004), access to financial services was a strong predictor of production improvement and farmer’s income at (p=.002), a positive and a significant relationship were observed between availability of quality farm inputs and banana production (at p=.023), The study further discovered that ready market was a strong predictor of production and small holder farmer’s income at (p=.003) and Lastly, a positive and a significant relationship were observed between banana varieties grown and banana production as well as income at (p=.005). The study recommends that the government, NGOs, Ministry of Agriculture, Animal, Industry and Fisheries in collaboration be established with the aim of implementing innovative agricultural strategies geared towards banana productivity increments, there is also a need for the government to provide enough facilities to extension agents that will help them facilitate enhanced training to farmers and inform them of new techniques in farming, there is a need for the government to provide some production inputs at subsidized cost.

Leaves litterfall and nutrient inputs from four multipurpose tree/shrub species of homegarden agroforestry systems

BackgroundAs compared to natural forest ecosystems, soils under agroecosystems are more subjected to changes in physical and biochemical attributes. But, tree species that are retained and/or planted on these agroecosystems replenish soil fertility through the influence of leaves litterfall quantity and quality. Tree species-related differences in the quantity and seasonality of leaves litterfall and the associated amounts of annual returns of nutrient elements were assessed from four multipurpose tree/shrub species (Erythrina brucei Schweinf, Cordia africana Lam., Grevillea robusta R. Br. and Malus sylvestris Mill.) in homegarden agroforestry systems. Five replicates of two leaf litterfall traps per species were randomly positioned beneath the subcanopy area for 12 months, totaling 40 litterfall traps distributed among the four species.ResultsThe results of this study suggested that total annual leaves litterfall varied significantly among species (ranging from 171.18 to 962 kg ha− 1), with the combined per tree mean monthly (28.13 kg tree− 1), per tree annual (331.10 kg tree− 1 year− 1) and per area basis total annual (9439.33 kg ha− 1) leaves litterfall production. A clear seasonal leaves litterfall pattern with varying peaks was observed for the multipurpose tree/shrub species in the present study, with a bimodal distribution pattern for E. brucei and C. africana and a unimodal distribution pattern for G. robusta and M. sylvestris. Similarly, both the concentrations and inputs of nutrients from the leaves᾽ litterfall showed considerable variations among species (p < 0.05). Among the investigated species, C. africana and E. brucei were found to be the best in terms of carbon (C) and nitrogen (N) return, G. robusta the best in terms of phosphorous (P) return, and C. africana as well best for potassium (K) return. The combined mean annual nutrient inputs recorded for all the species were 3125.32 kg C ha− 1 year− 1, 149.70 kg N ha− 1 year− 1, 54.86 kg K ha− 1 year− 1, and 3.56 kg P ha− 1 year− 1.ConclusionsLeaves litterfall amount differed among tree species as influenced by tree species characteristics (canopy area, diameter at breast height (DBH), height), but no cause-effect relationship with age and climate (monthly precipitation and temperature).

Comparison of Organic Fertilizer vs. Inorganic Fertilizer on the Growth of Cucumber (Cucumis sativus L.)

Chemical fertilizers have been utilized extensively over last five to six decades. They significantly contribute in damaging the ecosystem, including the soil properties and the health of the future generation. Organic farming is employed as a substitute&nbsp;to obtain better and healthier output. To increase output and replenish soil fertility without harming the environment or having any negative impacts on human health, organic fertilizers such as sawdust, cow dung&nbsp;and cow&nbsp;urine are used instead of chemical fertilizers. Nowadays, organic farming is widely practiced around the world. Efforts were made to study the effects of organic and inorganic fertilizers on the growth of cucumber (Cucumis sativus L.). Experiment was conducted in pots with four treatments i.e., control (water and soil), organic (cow dung, cow urine, sawdust), inorganic (NPK) and mixture of organic and inorganic. The parameters observed were stem height, number of leaves and the length of leaves. Antimicrobial activity of cucumber leaves, seeds and cow urine was checked on different bacterial strains including E. coli, Pseudomonas sp. and Salmonella sp. Phytochemical analysis was conducted to analyze the presence of alkaloid, carbohydrate, tannins, saponins, flavonoids, terpenoids, phenol and anthraquinone content in cucumber. In comparison to alternative treatments, organic cucumber cultivation produces higher growth rates. Cow urine was more effective against E. coli, moderate against Pseudomonas and resist against Salmonella. The seed extract of cucumber was more effective against Salmonella and less effective against E. coli. The leaf extract is more effective against Pseudomonas and less effective against E. coli. In cucumber leaves alkaloids, carbohydrate, tannins, saponins, flavonoids, terpenoids, phenol and anthraquinone content are present.

English

Orange-fleshed sweet potato is an important source of macro-and micronutrients for humans, particularly in resource-poor rural communities. However, sweet potato cultivation removes large amounts of nutrients from the soil. Hence, soil fertility replenishment is vital to secure long-term food production. The lack of access to fertilizers hinders the ability of farmers to supply and replenish soil nutrients, intensifying food insecurity. This study aimed at identifying locally available organic residues and agricultural practices with potential application in soil fertility management to prevent soil degradation in southern Mozambique. We conducted a survey to gather information on the farmers&rsquo; demographics and farming systems of 107 orange-fleshed sweet potato farmers. Results show that more than 70% of farmers use agroecological practices such as intercropping and crop rotation, and more than 90% indicated having residual crop biomass after harvest. Most cultivated crops, such as lettuce, beans, etc., are harvested in July-August, before the start of orange-fleshed sweet potato cultivation. Thus, there is potential for the application of crop residues as an organic amendment for orange-fleshed sweet potato cultivation. Nevertheless, farmers need support to adopt soil fertility management based on locally accessible resources, therefore ensuring extension services focused on the long-term benefits of sustainable practices are vital. Key words: Crop residue, organic agriculture, smallholder, survey.

Assessment of the production and importance of cowpea [Vigna unguiculata (L.) walp]: Cases from selected districts of southern Ethiopia

Cowpea (Vigna unguiculata L.Walp) is an important legume in the hot, dry tropics and subtropics of sub-Saharan Africa, serving a multiple role for the livelihoods of millions of relatively low-income people. The entire plant can be used for either human or livestock consumption and with considerable drought-tolerating capacity. Tender young leaves, green pods and matured seeds are used as human food. Moreover, the crop serves for sustainable soil fertility improvement due to its excellent nitrogen-fixing capacity. However, its production and utilization are limited in Ethiopia partly due to dependence on the conventional agronomic practices and lack of information on its wide ranging uses. This study was conducted to assess the cowpea agronomy and the contributions the crop has in the livelihoods of farmers at Loka-Abaya and Humbo districts of Southern Ethiopia. Multi-stage sampling techniques were employed to achieve the set objectives. Both primary and secondary data were collected to solicit the required information. The data were subjected to descriptive and inferential statistics such as multiple linear regression model using the SPSS Software version 20 and STATA 13. Multiple linear regression model results showed that education, land size, climate information access, credit access, lack of market chain, availability of seed of improved varieties, and pests significantly (P&lt;0.001) affected cowpea production in the studied areas. The trend analysis showed that the cowpea yield and production area coverage is increasing in Humbo District whereas, a decreasing trend was observed at the Loka Abaya. According to the household interview data, about 76 % of the respondents reported a decrease in the cultivated area of cowpea. According to the respondents, lack of access to improved seed and lack of extension support services contributed 79 % and 73 %, respectively to the low yield observed in the area. The majority of the respondents cultivate cowpea as intercropping and rotation with cereals and in the main field with the main purpose to replenish soil fertility (97 %). On the other hand, 62 % of the respondents cultivate cowpea for home consumption. According to the survey result, 48 % of the respondents use the matured grain for consumption. The production trends of the cowpea are highly variable mainly due to less attention paid by the extension systems to boost the yield of the crop, reliance of farmers on local varieties, pest occurrence and poor market chain. Therefore, modern production technologies including the supply of improved varieties of seed with their full production package should be introduced to the area so as to improve the yield and optimize its contribution towards achieving food security.

The impacts of agroforestry interventions on agricultural productivity, ecosystem services, and human well-being in low- and middle-income countries: A systematic review.

The impacts of agroforestry interventions on agricultural productivity, ecosystem services, and human well-being in low- and middle-income countries: A systematic review.

Soil fertility management practices for faba bean (Vicia faba L.) production in Wolaita zone, Southern Ethiopia

Faba bean is an important food security crop in Southern Ethiopia. Understanding the soil fertility management practices of faba bean farmers could aid in finding a method to replenish soil fertility. However, information on the type and extent of soil fertility management practiced by smallholder faba bean farmers is scarce. Therefore, a study was conducted in the districts of Damot Gale and Sodo Zuria in Wolaita zone in Southern Ethiopia to assess soil fertility management practiced by farmers for faba bean production. In the 2019 main cropping season, 310 farmers were purposively selected by using Yamane’s simplified formula to calculate the sample size and a short structured questionnaire was used to elicit information. The results revealed that faba bean production in the districts studied was constrained by scarcity of arable land that resulted in extensive exploitation of soil nutrients, poor inherent soil fertility, and soil acidity. Poor soil fertility limited grain yield productivity about 57.4%. Additionally, 36.5% of the farm yield was constrained by soil acidity. However, only 27.7% of farms managed the soil by using mineral fertilizers; 32.3% applied farmyard manure, 3.5% used liming, and 2.9% used fallowing. Consequently, the average grain productions of both fertilized and unfertilized faba bean farms were far less than the national average yield of 2.1 t ha-1. The study concluded that soils of the study districts are managed inadequately to enhance their fertility and improve crop yield.

Speed breeding in pulses: an opportunity to improve the efficiency of breeding programs

Pulses form an important component of the human diet, provide animal feed, and replenish soil fertility through biological nitrogen fixation. However, pulse breeding is a time consuming process. Most of the traditional breeding programs take 10–15 years to release an improved cultivar. In the breeder’s equation, a model of the expected change in a trait in response to selection, cycle time is the most powerful parameter for increasing genetic gain. Shuttle breeding, double haploids and in vitro culture are some of the methodologies that have been developed; however, they have not been able to be implemented efficiently in the breeding programs for pulses. In this context, speed breeding emerges as a technology that allows increased efficiency of the programs, reducing costs and the work required. The technique uses optimal light quality, light intensity, daylength and temperature control to accelerate photosynthesis and flowering, coupled with early seed harvest. It can be integrated with other breeding technologies, does not include transgenesis or gene editing, and is presented as a revolution to increase the efficiency of the programs. We present different advances in pulse breeding programs and propose a speed breeding system for pea (Pisum sativum L.) that includes hybridisations and advancing generations in a growth chamber. This review concludes by highlighting the opportunities and challenges to incorporating speed breeding into pulse breeding programs.

Nanofertilizer and its application in horticulture

Current horticultural practices are being upgraded and updated by use of various technologies including nanotechnology. Use of nanotechnology for developing nanofertilizers could improve the nutrient use ef?ciencies, reduce nutrient loss, replenish soil fertility, increase crop yield, maintain ecosystem, soil health and curtail serious soil problems. Nano-fertilizers are formulated to deliver and emit nutrient tardily and deliberately. Regular release of nutrients by nanofertilizers help in augmenting nutrient use efficiency beyond several related adverse outcome. Nanofertilizers may increase the fruit yield and quality of various horticultural crops which will inturn increase the nutritive content of products as well as increase the global food security. The present review discuses different aspects of nanofertilizer application in horticulture.

Manure recycling from urban livestock farms for closing the urban\u2013rural nutrient loops

Rapid urbanization in developing countries is attracting urban livestock farming, which is associated with feed nutrient imports and manure nutrient accumulations. Here, we report on manure nutrients (N, P and K) production on urban livestock farms in Addis Ababa and Jimma in Ethiopia, and estimate manure recovery on these farms and its recycling in urban, peri-urban and rural crop farms. Estimates were based on data from farm surveys, statistics, literature and model calculations. Urban livestock farms had on average 13 tropical livestock units and positive N, P and K balances. Urban crop farms had negative N and K balances, and did not use manure from urban livestock farms. We estimated that 0.5–2.6 Gg N, 0.2–0.8 Gg P and 0.9–3.7 Gg K can be collected in manure from the 5,200 urban livestock farms in Addis Ababa year−1, and can be recycled in crop land. Two manure allocation strategies were explored: balanced P fertilization and balanced N fertilization. The former allowed greater precision in matching nutrient supply to demand, and was associated with greater manure transport and distribution, up to rural areas. Manure recycling has several benefits: synthetic fertilizer savings (75–300 million Ethiopian Birr year−1 for Addis Ababa), soil fertility replenishment, and reductions in water pollution. However, there are various cultural, educational and institutional barriers for manure recycling. We argue that more quantitative data and scenario analyses are needed for deliberative decision making and for exploring more sustainable development pathways of urban livestock farms, re-connected to crop farms via manure recycling.

Perception of Farmers’ on Soil Fertility Problems and Replenishment Technologies in the North Rift Region of Kenya

This paper investigates the farmers’ perception on soil fertility replenishment technologies in the North Rift Region of Kenya. A survey was conducted in Trans Nzoia and Uasin Gishu counties of the North Rift Region of Kenya. A total of 108 respondents were interviewed. A two stage random sampling technique was employed in the study. In the first stage, farmer groups growing maize as the main crop were selected. The second stage involved the selection of farmers who were practicing cereal banking for ease of marketing of their produce. A survey and field demonstration plots were adopted. On-farm demonstration were carried out and used to ascertain the farmers’ perception towards the technologies. A structured questionnaire was administered to them to elicit information on their perception on soil fertility replenishment technologies (SFRT). Descriptive statistics and the multiple regression analysis was done using a Statistical Package for Social Sciences (SPSS). The results revealed that farmers perceived that technologies could be used to address the declining soil fertility. The inputs were affordable available, the Ministry of Agriculture, Livestock and Fisheries (MOALF) was effective in disseminating the technologies and that the technologies could work on any farm at mean score of 3.5, 4.1, 4.0, 3.4 and 4.6 out of 5.0 respectively. Farmers in Trans Nzoia county identified lack of capital (70.4%) compared to Uasin Gishu (39.9%) as the greatest challenge in the adoption of SFRT technologies. Credit schemes that offer loans with low interest rates should be established to enable farmers have access to credit.

Effect of starter nitrogen and phosphorus fertilizer rates on yield and yield components, grain protein content of groundnut (Arachis Hypogaea L.) and residual soil nitrogen content in a semiarid north Ethiopia

Increasing costs of chemical fertilizers, environmental concerns of their application and demand for protein foods, placed an extensive interest in growing of legume crops for human nutrition, and soil fertility replenishment. This study was conducted to investigate the effects of nitrogen (N) and phosphorus (P) fertilizers on parameters of phenology, growth performance, grain yield, yield components, grain protein content of groundnut, and residual soil nitrogen content in the northern Ethiopia during the growing season of 2017. Three levels of N (0, 15 and 30 kg ha−1) and four levels of P2O5 (0, 23, 46 and 69 kg ha−1) were set in factorial combinations of randomized complete block design with three replications. Results showed that an average total biomass yield increased by 22.5% for separate individual application of 15 kg N ha−1 and by 16.6% for 46 kg P2O5 ha−1 compared to control plots. Haulm yield increased by 29.17% for plots treated with N fertilization compared to control plots. Average pod yield increased by 85.4% for a combined application of 15 kg N ha−1 and 46 kg P2O5 ha−1 fertilizers compared to the control plots. Plots fertilized with the highest combined rates of N and P have attained lower grain yield compared to the combined application of 15 kg N ha−1 and 46 kg P2O5 ha−1. The highest grain protein contents were obtained for a combined application of 30 kg N ha−1 and zero P, and 15 kg N ha−1 plus 46 kg P2O5 ha−1. The highest N harvest index was obtained for control treatments and for plots treated with combined application of 15 kg N ha−1 and 46 kg P2O5 ha−1. Residual soil N content increased by 119% on plots with combined application of 15 kg N ha−1 and 46 P2O5 ha−1 compared to control plots. Based on our results, combined application of 15 kg N ha−1 and 46 kg P2O5 ha−1 was recommended for increasing grain yield, grain protein content and residual soil nitrogen. The results of this study are crucial to improve groundnut productivity, grain protein content and also to provide implication on soil fertility management in a crop rotation system.

English

Phosphate rock (PR) deposits are the major source of phosphate (P) fertilizers for soil fertility replenishment. The demand for P fertilizers in the year 2014 was 42,706,000 tons and was expected to reach 46,648,000 tons in 2018. Majority of PR deposits are found in only a few countries including Morocco, USA and China. There is however conflicting information on the extent of world PR reserves, therefore, complicating the ability to accurately determine their lifespan. Consequently, proper planning on the utilization of this resource is hampered. Two schools of thought have emerged in regard to the longevity of the PR reserves. Some argue that there is imminent depletion of this resource and the world should therefore be prepared for a looming food crisis. However, based on the most recent estimates of 290 billion tons of PR reserves, some scientists have predicted that the PR reserves will be depleted between the years 2311 and 2411 and therefore conclude that there is no immediate course of alarm. What is not in doubt, however, is the finiteness of PR reserves. Therefore, an approach that encourages society to adopt a sustainable utilization of this phosphate resource should be advocated as an insurance against food insecurity. Key words: Food security, phosphate rock depletion, sustainable agriculture. &nbsp

Soil Fertility Management for Better Crop Production

Increasing crop productivity per unit of land area to meet future food and fiber demand increases both soil nutrient removal and the importance of replenishing soil fertility through efficient nutrient management practices. Significant progress in enhancing nutrient-use efficiency in production agriculture requires improved estimates of plant-available nutrients in the root zone, enhanced crop response to applied nutrients, and reduced offsite nutrient transport. This special issue, Soil Fertility Management for Better Crop Production, presents 15 manuscripts that advance our knowledge of interrelated soil, plant, and management factors important to increasing the nutrient availability and crop recovery of applied nutrients.

Supplementing grass-based cattle feeds with legume leaves and its effects on manure quality and value as a soil improver for an Anthropic Ferralsol in Rwanda

AbstractCombined use of lime, animal manure and inorganic fertilisers is effective in replenishing the fertility of degraded acid soils. However, many smallholder farmers lack access to sufficient amounts of these inputs to improve the fertility and reduce the aluminium toxicity of Ferralsols. Organic manures are available but often have low nutrient content, which limits their ability to supply nutrients to soils. In a two-factor field experiment over four seasons on an Anthropic Ferralsol in Southern Province, Rwanda, we assessed (i) the effect of cattle manure on soil properties at a reduced rate affordable to smallholder farmers compared with that of NPK fertiliser applied, with and without lime also at a reduced rate, and (ii) the effect of supplementing grass in a basal cattle diet with legume leaves on manure quality and its effect on soil properties. Manure from cattle fed only the grass Chloris gayana (grass-only manure) and from cattle fed C. gayana supplemented with Acacia angustissima leaves (grass+legume manure) was applied at 5 t dry matter ha-1 (25% of the recommended rate) at the beginning of each growing season. NPK was applied as split doses supplying a total rate of 70 kg N ha-1. Lime was applied annually at a rate of 2.0 t CaO ha-1, which was 25% of the rate required to neutralise total acidity at the site. All amendments were applied only to the soil surrounding the maize plants (planting stations), which is estimated at 25% of the plot area. Maize stover was left on plots after harvest and planting stations were retained over all growing seasons. All treatments altered soil properties at the planting stations. Lime generally increased pH but there was no significant difference between lime plus manure treatments and non-limed manure treatments. Soil organic carbon concentration and cation exchange capacity were higher in manure and NPK treatments than in non-fertilised treatments. The manure treatment increased soil water-holding capacity compared with the NPK and non-fertilised treatments. There was no significant difference in total N, Ca2+, Mg2+ and K+ between the NPK and manure treatments. Micro-dosing animal manure can thus replace mineral fertiliser plus lime for soil fertility replenishment in smallholder farming. Grass+legume manure contained higher concentrations of total N, Ca, Mg, K and Na than grass-only manure, but its effect on soil properties did not differ significantly from that of grass-only manure.

Land use and management effects on volcanic soils in West Sumatra, Indonesia

In this study, we aimed to assess the influence of land use and management on the fertility characteristics and pedogenic indicators of volcanic soils. Our study area was a mountainous area located in West Sumatra, Indonesia, where local farmers intensively cultivate vegetables by applying high amounts of chemical fertilizers and agrochemicals. Some negative impacts of conventional management were observed in the vegetable fields: soil acidification and loss of organic matter, with descended soil pH and increased acidity as well as decreased contents of exchangeable bases and with decreased amount of organic C. These impacts were not effectively mitigated by positive factors such as increased P availability and decreased capacity for P fixation. Continued cultivation over the years compounded the effects of these changes. Organic farming was advantageous in terms of soil fertility maintenance as it alleviated negative impacts compared to conventional farming. Natural fallow was effective in replenishing soil fertility as indicated by a significant increase in organic C, total N, and exchangeable Ca and Mg contents compared to the vegetable fields. The degree of replenishment was enhanced with a longer period under fallow; however, the natural fallow decreased P availability and increased P fixation capacity. Calliandra calothyrsus fallow further accelerated soil acidification, regardless of the rapid increase in the organic C and exchangeable bases contents. The adverse effects of Calliandra fallow were associated with the formation of humus–aluminum complexes to an extent that it changed from Sil-andic to Alu-andic Andosols.

Optimizing Soil Fertility Management Strategies to Enhance Banana Production in Volcanic Soils of the Northern Highlands, Tanzania

Banana is an important crop in high altitude areas of Tanzania, grown widely both as a food staple and as the main source of income. However, its production is constrained by low soil fertility, a result of gradual nutrient mining by the crop. Currently, soil fertility management in banana-based farming systems in the country relies mainly on applications of animal manure. However, the amount of manure produced in most farms is not enough to replenish soil fertility due to the small number of animals kept by smallholder resource-poor farmers who are the major producers in the country. Field experiments were conducted at three sites with varying soil types and contrasting weather conditions along the altitudinal gradients on the slopes of the volcanic mountains of Kilimanjaro and Meru, northern Tanzania to (1) investigate the effect of mineral nitrogen (mineral N) fertilizer applications on the growth and yield of Mchare banana (Musa spp., AA, a traditional East African highland cooking banana sub-group), at the four levels of 0, 77, 153, and 230 kg N ha−1 year−1 as a starter strategy to improve the current soil fertility management strategies, and (2) evaluate the effect of the combined use of inorganic and organic N sources on growth and banana fruit production as an alternative strategy to manage soil fertility and minimize animal manure requirements. The treatment factors were trial sites (Tarakea, Lyamungo, and Tengeru) as the main factor and N fertilization strategies (as urea alone, sole cattle manure, and in combination with urea, sole common bean (Phaseolus vulgaris L.) haulms as well as in combination with urea) as a sub factor. Bean haulms and cattle manure were applied each year for two years. Fertilization at 153 kg N ha−1 year−1 derived solely from urea significantly (p &lt; 0.001) resulted in high yield increment of up to 42% relative to the control. However, the increase was highest (52%) with the same N dose derived from cattle manure in combination with urea at 50% substitution. Sole bean haulms resulted in a smaller yield increment, the same as the lowest N dose from the sole urea fertilization treatment. The study concludes that soil fertility management in smallholder banana-based farming systems should not solely rely on animal manure and mineral fertilizers.

Comparing Poultry Manure to Inorganic Fertilizer and Their Combination on the Growth and Yield Performance of Omankwa Maize Variety

Aims: Major effect of soil fertility decline is the observed reduced food production in most African countries, including Ghana. In order to sustain soil and crop productivity, it is necessary to explore alternative soil fertility replenishment strategies, which are effective and affordable to farmers, especially the smallholder farmer.&#x0D; Study Design: A RCBD in three replications with each block with dimension 4 m × 3 m using spacing of 0.75 m and 0.4 m inter and intra and inter-row.&#x0D; Place and Duration of Study: The research work was conducted at the CSIR-Crops Research Institute, Kumasi between April 2016 - December 2016 using Omankwa a released maize variety from CSIR-Crops Research Institute, Kumasi, Ghana.&#x0D; Methodology: There were six treatments per rep and each rep was randomized. Treatments were as follows; control (no fertilizer or poultry manure); T1 (100% Poultry manure two weeks after planting of maize), T2 (100% (N.P.K) two weeks after planting of maize), T3 (25% Poultry manure and 75% NPK fertilizer), T4 (50% Poultry manure and 50% NPK fertilizer) and T5 (75% Poultry manure and 25% NPK fertilizer). &#x0D; Results: Results from the study showed that Omankwa performed better under treatment T1 better than other treatments T4 and T5 even though T4 and T5 perform better in other parameters measure for the experiment but did not results in grain yield for Omankwa.&#x0D; Conclusion: The use of poultry manure still remains to be the best source as alternative to soil nutrient used for often better yield of crop production but for lack or availability of poultry manure, the poultry manure con be supplemented with NPK a synthetic fertilizer to obtain optimum grain yield in maize production.