Soil Fertility Depletion Research Articles

Improvement of mineral nutrient content of tomato through selection of cultivars and soil fertility

Depleted soil fertility and high-yielding cultivars have been associated with low nutrient contents in vegetables. This study explored if elemental nutrient concentrations in tomato (Lycopersicon esculentum Mill.) can be increased through selection of cultivars and nutritional regimes. Cultivars with different phenotypes of heirloom and modern origins were studied in field experiments in two years. Chemical fertilizer (10-10-10), compost, and an organic fertility regime of soybean meal, bone meal, and potassium sulfate were assessed for their effects on growth and composition of fruits of the cultivars. Differences in nutrient concentrations between modern or heirloom cultivars or among fertility treatments were small or non-significant. Differences among individual cultivars for each element were large with some cultivars having nearly twice the concentrations of nutrients of others and with considerable uniformity in cultivar rankings among the elements. This work suggests that cultivars can be selected for production of nutrient-dense tomatoes.

Differential Response of Biomass Production and Nitrogen Uptake of Vegetable Amaranth to Two Types of Poultry Manure from Nigeria and Canada

Amaranthus cruentus is one of the sixty Amaranthus species of world. It is widely grown as a green leafy vegetable and for its grain in many tropical countries of Africa, Central and South American, Canada, Mexico and parts of Asia. Depleted soil fertility under intensive cultivation is a major limitation to production of the vegetable. The study investigated the effects of two types of poultry manure on biomass yield and nutrient uptake of Amaranth cruentus in a greenhouse at the University of Manitoba, Winnipeg, Manitoba, Canada in 2011. The experiment was a 2 × 3 × 3 factorial arranged into a Randomized Completely Block Design and replicated three times. The factors were two soil types, two sources of poultry manure and urea, and N rates at 0, 60 and 120 kg⋅N⋅ha−1. Nitrogen uptake by the plants that treated with poultry manure from Canada (PMC) and Urea was 172.5 vs. 171.4 mg⋅pot−1 and 169.5 vs. 163.7 mg⋅pot−1 respectively which were significantly greater than the poultry manure from Nigeria (PMN), 100.6 mg⋅pot−1 and 110.0 mg⋅pot−1 for Red River and Glenhope soil series, respectively. Nitrogen uptake was similar at the N rates of 60 and 120 kg⋅N⋅ha−1 (140.7 vs. 155.6 mg⋅pot−1) in the Red River soil, while N uptake at 120 kg⋅N⋅ha−1 was greater than at 60 kg⋅N⋅ha−1 in Glenhope soil. Shoot dry matter of the vegetable grown in soils treated with PMC and urea was significantly greater than from PMN in Red River soil (10.1, 9.6 and 6.7 g⋅pot−1) and in Glenhope soil (8.8, 8.1 and 6.4 g⋅pot−1). Phosphorus, K, Ca and Mg uptake at 60 and 120 kg⋅</

Understanding farmers' investments in sustainable land management in Burundi: A case‐study in the provinces of Gitega and Muyinga

AbstractUnderstanding farmers' decision‐making to tackle land degradation by means of sustainable land management (SLM) practices is essential for policy makers. The main objective of this study was to identify factors that influence farmers' investments in SLM. A survey was conducted in two provinces of Burundi (Gitega and Muyinga) among 160 households. Methods for data analysis comprised descriptive statistics and multinomial logistic regression. It was derived that both provinces experience severe land degradation, with soil erosion experienced by 88% of the farmers and soil fertility depletion by 92%. Furthermore, findings show that occurrence of soil erosion on the farm (p = 0.025), access to credit (p = 0.022), education level (p = 0.040), engagement of the household head in farming (p &lt; 0.001), and age of the household head (p = 0.050) are significantly and positively associated with higher investments in SLM. Moreover, the findings reveal that the yearly costs per farmer associated to the SLM practices' implementation ranged from US$10.08 for soil and water conservation practices up to US$36.24 for organic fertilizers. Therefore, in order to foster SLM, we recommend policy makers in Burundi to improve access to credit markets in rural areas and enhance efforts to strengthen smallholders' skills, bringing as such more integrated and effective solutions to cope with land degradation problems.

Low-cost and environmental-friendly Triticum aestivum-derived biochar for improving plant growth and soil fertility

ABSTRACT Biochar and biochar–fertilizer concoction is imperative to subjugate reduced plant growth and soil fertility depletion which is a constraint for sustainable agriculture. The aspiration of the current research was to determine the plant growth response to wheat straw-derived biochar annexation in soils from two regions: Rawalpindi (semi-arid) and Thar (arid). Wheat straw (Triticum aestivum) was pyrolyzed at 300°C in a low-cost biochar retort kiln at different concentration rates (0%, 1%, 3%, and 7% by mass). Growth trend of Sorghum bicolor was observed in these soils for 40 days in a greenhouse. Fertilizer (NPK) (8.58% N, 4.39% P, and 3.48% K) was added to soil on the third day of seed germination. Soil physicochemical analysis, plant growth, and dry matter yield evaluation after the treatment signified the concomitant increase in dry matter yield along with enhanced soil fertility and plant growth.

Influence of phosphorus application on yield, yield components, and quality of linseed

Soil fertility depletion coupled with improper fertilization is one of the major constraints limiting linseed production in Ethiopia. Experiment was conducted in 2014/2015 on Nitisol in southeastern Ethiopian highlands to study the effect of phosphorus (P) fertilizer rate on yield, yield components, and oil content of linseed. It comprised of six levels of P fertilizer (0, 5, 10, 15, 20, and 25 kg P ha−1) arranged in randomized complete block design with three replications. Results revealed that P fertilization brought significant effect on biomass yield, harvest index, plant height, number of capsules per plant, and kernel size. However, it didn’t significantly increase seed yield and oil content on linseed. Considering its influence on increasing biomass yield and improving yield components, application of 5 kg P ha−1 has been recommended for replenishing the extracted P, maintaining soil fertility and improving linseed production on Nitisols of southeastern Ethiopian highlands and other similar agro-ecologies.

Bio-intensive Modulation of Sugarcane Ratoon Rhizosphere for Enhanced Soil Health and Sugarcane Productivity Under Tropical Indian Condition

Intensive cropping and exhaustive nature sugarcane crop in tropical India have led to depletion of inherent soil fertility resulting in serious threat to sustainable sugarcane production. Improving soil organic matter and soil fertility are important factors for sustainable sugarcane production. Microbial consortia comprising of Trichoderma viride, Humicola spp, Paecilomyces lilacinus, Gluconacetobater diazotropicus, Azospiriillum brasilense, and Bacillus subtilis have great potential to recycle crop residue and restore soil fertility which eventually promote sugarcane growth. Field experiments with in situ trash management in plant crop and bio-intensive modulation of sugarcane ratoon rhizosphere in ratoon crops were conducted during 2014, 2015 and 2016 at ICAR—Sugarcane Breeding Institute, Coimbatore, Tamil Nadu, India. The results revealed that green manuring with sunnhemp, in situ trash management and application of 280:62.5:120 kg NPK ha−1 in plant crop sustained the soil health by way of reducing soil bulk density (1.26 kg dm−3), lower soil penetration resistance in the ratoon rhizosphere (1.79, 1.82 and 1.75 MPa) and higher soil organic carbon (0.52%) which in turn increased ratoon cane yield 12.24% (99.02 t ha−1) and sugar yield by 8.64% (12.83 t ha−1) over the control. Further, bio-intensive modulation of ratoon rhizosphere by off barring, trash shredding plus soil incorporation with microbial consortia and application of 350:62.5:120 kg NPK ha−1 in ratoon crop recorded significantly higher cane yield (100.95 t ha−1) and sugar yield (13.19 t ha−1) over the control. The improvement in cane yield and sugar yield to the tune of 16.35 and 14.10% due to bio-intensive modulation of ratoon rhizosphere over control have clearly established that productivity of sugarcane ratoon can be significantly improved with balanced use of fertilizers, green manuring, crop residue recycling and microbial consortia application. Similarly, bio-intensive modulation of sugarcane ratoon rhizosphere (S3) with lowest soil bulk density (1.26 kg dm−3) and soil penetration resistance values (1.69, 1.81, and 1.75 MPa) was found effective in minimising the soil compaction and improving nutrient availability (NPK) with build-up of soil microbial population than control (Trash removal). Based on the results of 3-year field experiments, it is concluded that sunnhemp green manuring and in situ sugarcane trash management coupled with application of 280:62.5:120 kg NPK ha−1 in plant crop followed by bio-intensive modulation of ratoon rhizosphere including off barring, trash shredding and soil incorporation with microbial consortia and application of 350:62.5:120 kg NPK ha−1 in ratoon crop can be recommended for sustaining soil health and sugarcane productivity under wide-row sugarcane planting systems of tropical Indian condition.

Available status and changing trend of micronutrients in floodplain soils of Bangladesh

Soil micronutrient deficiency has arisen in Bangladesh as a consequence of soil fertility depletion with time. Increasing cropping intensity and cultivation of modern varieties with high yield potential are the major reasons of nutrient depletion from soil, which results in decline of crop yield. With an objective of studying delineation of soil micronutrient status, their depleting trend over time, relationship with other soil variables and interrelationship among micronutrients, a study was carried out in Old Meghna Estuarine Floodplain (AEZ 19) soils of the country. In the present study, soil analysis of top soils (0-15 cm soil depth) shows that availability of Zn and B declined after a decade of time. However for other micronutrients, viz. Cu, Mn and Fe, still prevailing high status. Micronutrient levels of subsoil (15-30 cm soil depth) were in general lower than those of top soils. The soil Zn had significant positive correlation with clay content (r=0.712**) and its availability was found influenced more by clay fraction in case of higher Zn concentration (&gt;1.35 μg g-1) than lower concentration (&lt;1.35 μg g-1). The Cu content in soil was positively influenced by soil clay content (r=0.267*), organic matter content (r=0.279*), N content (r=0.579**) and Mg content (r=0.364**), and was negatively influenced by soil pH (r= -0.347**) and P content (r= -0.340*). Concerning interrelationship among soil micronutrients, Cu content showed positive interaction with Zn content (r=0.244) and negative interaction with B content (r= -0.255). In sub soil, except soil B content, all other micronutrient contents were negatively correlated with soil pH. Only Cu content was significantly correlated (r=0.362**) with clay content. There exists positive relationship between soil organic matter and Zn (r=0.269*), Cu (r=0.357**) and Fe content (r=0.362**). The Zn, Cu and Fe content in soil was positively correlated with soil N content, r values being 0.455**, 0.526** and 0.659**, respectively.SAARC J. Agri., 16(1): 35-48 (2018)

Social, Economic and Environment Sustainability of Food Crop Production Systems: Sugarcane vs. Maize Production

Knowledge and technological inputs have played a significant role in the process of agrarian transformation of low input subsistence farming to high input commercial systems. The said transformation took place at a varying degree and nature owing to policy interests of successive governments though succeeded in meeting the growing food demand it eventually led to serious socio-economic and environmental implications and made food crop production systems (FCCPSs) more unsustainable. Many of them are irreversible and restoring the lost socio-economic values and degraded eco systems are challenging. Therefore, it has been a greater challenge today to achieving key sustainable development goals - Zero Poverty and No Hunger- while making FCPSs of small farmers sustainable. Identification of and encouraging wide-spread adoption of sustainable FCPSs is a must for that reason where policy directives could play a significant role. This study analyses and presents how effective are the agricultural sustainability indices as decision tools in the above mission. Primary data collected from two rain-fed FCPSs –maize and sugarcane- in the South East Dry Zone of Sri Lanka (SEDZ) in 2016 were used to assess the sustainability indices based on ten variables representing social, economic and environmental dimensions of sustainability of the FCPSs. The sample involved 149 farmers from Pelawatta sugarcane settlement scheme in Monaragala District and 130 maize farmers from Monaragala and Ampara districts. Additional data were collected through key informant interviews, focus group discussions and field observations. The results of the study showed that, both crops demonstrates approximately equally in social (SSI: maize - 0.566, sugarcane – 0.562) and environmental terms (ESI: maize – 0.260 and sugarcane – 0.259). Use of agrochemicals for weed control and fertilizer to compensate depleting soil fertility has become inescapable in both crops. Crop yield reduction owing to poor quality planting material is a major implication too. However, sugarcane is financially better off (FSI: 0.491) than maize (FSI: 0.342). Among the contributing variables were; higher contribution to family income (70 percent) and considerably high productivity (18850 kg/ac/yr) in compared to that of maize – 38 percent and 1764 kg of maize/ac/yr respectively. Currently there is a growing interest towards the expansion of croplands for both crops yet, the government is indecisive on the allocation of precious land resources. Therefore, the implications of the study contributes further dimensions to face the challenge of ending hunger and poverty through allocating land and other resources towards promoting sustainable FCPSs. Keywords: Agrarian transformation, Food crops, Sustainability, Policy directives, Resource allocation

Increasing area under pulses and soil quality enhancement in pulse-based cropping systems - Retrospect and prospects

India is the largest producer (25% of global production), consumer (27% of world consumption) and importer (14%) of pulses in the world (Anonymous 2016). Pulses accounted around 20% of the area under foodgrains and contribute around 7-10% of the total foodgrains production in the country. Productivity of pulses has improved by 65.07%, from 441 kg/ha in 1950-51 to 728 kg/ha in 2014-15. There is large scope to increase the area and production under pulses by utilizing existing rice fallows by growing chickpea, lentil, pea and khesari (lathyrus) after rice. But major hurdles in the successful cultivation of pulses in rice-fallows are the non-availability of quality seed, irrigation facilities, labour and other input availability. The production potential of pulses can be improved through introduction of short duration, nutrient responsive high yielding varieties and assured supply of quality seed, efficient nutrient management techniques and growth regulators, with supplemental irrigation. Declining factor productivity, depletion of soil fertility and over mining of native nutrient reserves, depletion of groundwater, increasing weed menace, and environmental pollution are major problems of rice-wheat cropping system. Introducing a legume (summer mungbean) in rice-wheat cropping system (RWCS) is one of the alternatives for overcoming some of these problems and provides additional economic returns and employment. Diversifying cropping systems with inclusion of pulse crops (mungbean or urdbean) can enhance soil water conservation, soil N availability, system productivity, soil physico-chemical properties such as aggregate stability, soil structure, bulk density and hydraulic conductivity, and soil biological activities. Moreover, levels of organic carbon, total N, available nitrogen, phosphorus, potassium and micronutrients increased significantly and substantially due to inclusion of mungbean in RWCS. Simultaneously the soil microbiological properties, viz. microbial biomass carbon, microbial biomass nitrogen and enzymatic (alkaline phosphatase, acid phosphatase, dehydrogenase, glucosidase, FDA hydrolysis, etc.) activities were also significantly higher in soils of rice-wheat-mungbean cropping system (RWMCS) than in RWCS. Therefore, this paper reviewed the inclusion of short duration pulses in different cropping systems in general and rice-fallows in particular which could help the farmers for getting the additional returns, besides improving soil physical, chemical and biological properties and help to sustain the agriculture productivity in the long-term.

Tef Yield Response to NPS Fertilizer and Methods of Sowing in East Shewa, Ethiopia

Purpose: Soil fertility maintenance is a major concern in tropical Africa which needs to tackle soil fertility depletion as fundamental constraints. Similarly, the traditional way of planting tef reduces the amount of grain production, promotes competition for inputs and causes severe lodging. In this view, a study was to investigate the effect of sowing methods and NPS fertilizer application on tef production.Research method: A factorial experiment was laid out in RCBD with12 treatment combination and three replications at DebreZeit Agricultural Research Center. The first factor included six NPS fertilizer rates and the second factor included two methods of sowing. Relevant data were gathered and analyzed using SAS and mean difference were compared using LSD.Findings: The results of the study revealed that the analysis of variance among fertilizer rates and method of sowing showed significant differences (P ≤ 0.05) on almost all the tef characters tested. The shortest mean days to 50% panicle emergence (57.5) of teff were obtained from 120kg of NPS fertilizer. However, applied NPS fertilizer showed no significant difference on tef physiological maturity. The highest grain yield (3.77t ha-1), biomass yield (10.09 t ha-1) and straw yield (6.32 t ha-1) were recorded from combination of 120 kg NPS fertilizer and transplanting method. Blended fertilizer together with transplanting had improved the number of effective tiller and grain yield, biomass yield as well as straw yield. Therefore, 120 kg ha-1of NPS fertilizer and transplanting method can be suggested as one effective way to maximize grain yield of tef.Research Limitation: Further validation and demonstrations across multiple areas would be necessary to make conclusive recommendation since the experiment was conducted for sole season and site.Originality/Value: This study provides insights for farmers and stakeholders to incorporate blended fertilizer for soil fertility amendment and in encouraging of tef transplanting technology for boosting production.

Tillage and cropping sequence effect on physico-chemical and biological properties of soil in Eastern Himalayas, India

Poor soil quality and low fertility are major limitations to agricultural intensification and increasing crop productivity under rainfed hill ecosystems of North Eastern Region (NER) of India. Intensive tillage and adoption of mono-cropping of rice (Oryza sativa L.) or maize (Zea mays L.) leads to depletion of soil fertility and crop productivity. A three year field experiment (2007–2010) was conducted at mid altitude of Meghalaya, India with eight cropping sequences [maize-rapeseed (Brassica campestris L. var. toria.), maize-pea (Pisum sativum L.), rice (Oryza sativa L.)- rapeseed, rice-pea, ricebean (Vigna umbellate Thunb.)-rapeseed, ricebean-pea, soybean (Glycine max L. Merr) – rapeseed and soybean-pea] under two tillage systems; conservation tillage (CST) and conventional tillage (CT). The objectives were to assess impact of tillage and cropping sequence(s) on soil quality and fertility after three years of the experiment. Soil moisture content and infiltration rate were significantly improved under CST relative to those under CT. The soil organic carbon (SOC) concentration was significantly higher under CST (23 g/kg) relative to that under CT (21.2 g/kg) at 0–15 cm soil depth. Available nitrogen (N), phosphorous and potassium, soil microbial biomass carbon (SMBC) and dehydrogenase activity (DHA) were also significantly higher in CST than those under CT. The cropping sequences did not affect the bulk density (ρb) and SOC significantly. However, available N, SMBC and DHA concentration were significantly higher under soybean-pea and soybean-rapeseed sequences as compared to others. During 2009–10, where rainfall received during the winter season was negligible, 4–70% higher yields of winter crops were observed under CST than those under CT. Thus, adoption of CST and soybean based cropping sequences offers an alternative to raise crops during the winter season on residual soil moisture and improve soil quality in eastern Himalayas.

Evaluating the Effectiveness of Different Rhizobia Strains and Their Effect on Crop Yields in Acid Soils of Western Kenya

Food insecurity in Sub - Saharan Africa (SSA) is on the rise due to soil fertility depletion and in Kenya, Nitrogen (N) is one of the widely deficient nutrients. Biological nitrogen fixation (BNF) can replenish N into the soil system. A study was carried out in acid soils at Koyonzo and Ligala sites of western Kenya to determine the effectiveness of different inoculants after agricultural lime application in enhancing BNF and yields of groundnuts (Arachis hypogea L.) and maize (Zea mays L.) intercrop. Red Valencia groundnut variety was intercropped with Hybrid 513D maize variety. A6w, W1w and V2w indigenous rhizobia strains were tested alongside a commercial rhizobia strain called biofix. Nitrogen treatment was included as a positive control. The results showed that inoculation significantly increased nodule number and weight per plant. There were significant differences among indigenous rhizobia in fixing N. Rhizobia inoculation accounted for 58.91% and 78.95% increase in the amount of N fixed above the control at Koyonzo and Ligala respectively. The strain that fixed the highest amount of N was A6w followed by V2w and W1w at both sites under the dolomitic soil amendment with the values of 14.67, 9.56, 3.53 and 11.37, 8.20 and 1.50 kg N ha-1, respectively at Koyonzo and Ligala sites. Rhizobia inoculation accounted for 80.96% and 47.09% maize yield increase at Koyonzo and Ligala respectively. The best inoculant A6w, gave maize yields of 3.76 and 2.78 t ha-1 at Koyonzo and Ligala, respectively. In conclusion soil amendment with dolomitic lime and inoculating groundnuts with rhizobia strain A6w resulted in increased groundnut and maize yields. This practice can, therefore, be adopted by farmers in western Kenya to improve the productivity of the groundnut maize intercropping systems.

A review of tef physiology for developing a tef crop model

Tef (Eragrostis tef (Zucc.) Trotter) is important for Ethiopian food security and a significant source of income for smallholder farmers in Ethiopia. In industrialized nations, tef is becoming a popular health food due to its lack of gluten and high nutritional value. Though tef is an important crop within Ethiopia, research on the crop has been limited. Crop models are an important tool for assessing food security, the effectiveness of management practices, and the impacts of climate change on crop production. The only existing crop models for tef are the FAO-AEZ crop growth simulation model, and the FAO AquaCrop model, which focuses on water limited crop production. The FAO AEZ model only produces final yields, which limits its applicability. The AquaCrop model has been validated using data from northern Ethiopia under current climate conditions without nitrogen limitations. As tef production spreads across the world, and Ethiopia suffers from soil fertility depletion and climate change, there is a need for a more comprehensive tef model. Tef, a short-day C4 crop, shows a high level of genetic diversity, resulting in large variation in water use, water use efficiency, growing season length, and even photosynthetic rate across cultivars. Tef quickly reaches a closed canopy, resulting in a higher early-season water use efficiency than wheat (C3 crop) or sorghum (C4 crop). Lodging is a significant yield limitation in tef, and is often exacerbated by fertilizer applications. There are several areas of tef research that have limited, or no, published data, especially on a field level, which will hinder future tef model development. These areas include the effects of temperature on photosynthesis and phenology, the effects of heat stress on senescence, the effects of elevated atmospheric CO2 on photosynthesis and transpiration, and a field level lodging model. By combining relevant information from other crops with the available tef literature, however, it should be possible to create a tef crop model prototype.

Review on: The Effect of Mixing Organic and Inorganic Fertilizer on Productivity and Soil Fertility

Depletion of soil fertility is a main problem to sustain agricultural production and productivity in many countries. The use of inorganic or organic fertilizer alone has both positive and negative effects on plant growth, nutrient availa-bility and the soil. Organic fertilizer improves physical and biological activities of soil but they have comparatively low in nutrient content, so larger quantity is required for plant growth. However, inorganic fertilizer is usually immediately and fast containing all necessary nutrients that are directly accessible for plants. But continuous use of inorganic fertilizers alone causes soil organic matter: degradation, soil acidity and environmental pollution. So the integrated nutrient management system is an alternative system for the sustainable and cost-effective management of soil fertility by combined apply of inorganic with organic materials resulting in rising soil fertility and productivity without affecting environment. The objective of the present review is to assess the effect of mixing organic with inorganic fertilizer on soil fertility and productivity. The study revealed that appropriate application of organic with inorganic fertilizers increases the productivity without negative effect on yield quality and improves soil fertility than the values obtained by organic or inorganic fertilizers separately.

Effects of Consecutive Two Years Tobacco Cultivation on Soil Fertility status at Bheramara Upazilla in Kushtia District

The study was conducted to determine the effects of tobacco cultivation on soil fertility and to compare the fertility status of tobacco based cropping patterns growing plot with adjoining non-tobacco based cropping pattern growing plots on randomly selected farmers plots for two consecutive years at Bheramara Upazilla (AEZ 11-High Ganges River floodplain) of Kushtia district by farmers practice, where tobacco farming is popular and on increase and to get a good scenario of soil fertility status of tobacco farming in Bangladesh. However, in tobacco plots, average pH value decreases from 7.86 to 7.44, Organic Matter from 1.95% to 1.78%, K from 0.46 meq/100 g to 0.32 meq/100 g, P from 13.98 ppm to 9.10 ppm, S from 16.22 ppm to 10.89 ppm and Zn from 0.70 ppm to 0.53 ppm after two consecutive years. Whereas, at non-tobacco plots, average pH value decreases from 7.83 to 7.65, Organic Matter from 1.86% to 1.79%, K from 0.42 meq/100 g to 0.36 meq/100 g, P from 14.44 ppm to 11.23 ppm, S from 14.01 ppm to 12.42 ppm and Zn from 0.74 ppm to 0.61 ppm after two consecutive years. Almost, results from all tobacco plots showed that farming of tobacco in a same land frequently reduces its fertility; therefore the farmers don’t get productivity neither from tobacco nor from other food crops latter. Therefore, tobacco cultivation leads to soil fertility depletion in soils in almost all cases and tobacco takes extra nutrients from soil which also negatively effect on soil fertility.

Optimize nitrogen fertilization location in root-growing zone to increase grain yield and nitrogen use efficiency of transplanted rice in subtropical China

The optimized nitrogen fertilization location differs in different rice-growing regions. We optimized nitrogen deep-point application in root-growing zone (NARZ) for transplanted rice in subtropical China. Field plot experiments were conducted over two years (2014–2015) in a double-rice cropping system to evaluate the effects of nitrogen (N) fertilizer location on grain yield and N use efficiency (NUE). Four different nitrogen deep-point application methods (DN) were compared with traditional broadcast application (BN) using granular urea. The results showed that grain yield, recovery efficiency of N (REN), agronomic efficiency of N (AEN), and partial factor productivity of N (PFPN) significantly increased 10.3–63.4, 13.7–56.7, 24.7–201.9 and 10.2–63.4%, respectively, in DN treatment compared to BN, respectively. We also find that DN treatments increased grain yield as well as grain N content, and thus grain quality, in comparison with conventional BN treatment. Correlation analysis indicated that significant improvement in grain yield and NUE mainly resulted from increases in productive panicle number and grain N content. In our proposed NARZ method, granular urea should be placed 0 to 5 cm around the rice seeding at a 12-cm depth druing rice transplanting. In NARZ, balanced application of N, P and K further improved grain yield and NUE over treatments with a single N deep-point application. High N uptake by the rice plant did not cause significant soil fertility depletion, demonstrating that this method could guarantee sustainable rice production.

Variation of mineral nutrient contents of modern and heirloom cultivars of cabbage in different regimes of soil fertility

ABSTRACTAn improvement in the mineral nutrient contents of fruits and vegetables is needed to offset reported declines in concentrations of these elements in fruits and vegetables. The declines have been associated with the high productivity of modern cultivars and to depleted soil fertility. This research addressed differences in mineral nutrient concentrations between modern F1 hybrids and heirloom cultivars of cabbage (Brassica oleraceae var. capitata L.)and among fertilization practices with conventional chemical or organic fertilizers and compost. Crop production was greater with the chemical or organic fertilizers than with the compost. Mineral nutrient composition did not vary between modern or heirloom cultivars or among fertilization regimes but varied among cultivars, suggesting that cultivar selection could lead to production of nutrient-rich cabbage. Neither mass of heads nor days to maturation of crops affected nutrient composition.

Microbial Phosphorus Solubilization and Its Potential for Use in Sustainable Agriculture.

The use of excess conventional Phosphorus (P) fertilizers to improve agricultural productivity, in order to meet constantly increasing global food demand, potentially causes surface and ground water pollution, waterway eutrophication, soil fertility depletion, and accumulation of toxic elements such as high concentration of selenium (Se), arsenic (As) in the soil. Quite a number of soil microorganisms are capable of solubilizing/mineralizing insoluble soil phosphate to release soluble P and making it available to plants. These microorganisms improve the growth and yield of a wide variety of crops. Thus, inoculating seeds/crops/soil with Phosphate Solubilizing Microorganisms (PSM) is a promising strategy to improve world food production without causing any environmental hazard. Despite their great significance in soil fertility improvement, phosphorus-solubilizing microorganisms have yet to replace conventional chemical fertilizers in commercial agriculture. A better understanding of recent developments in PSM functional diversity, colonizing ability, mode of actions and judicious application should facilitate their use as reliable components of sustainable agricultural systems. In this review, we discussed various soil microorganisms that have the ability to solubilize phosphorus and hence have the potential to be used as bio fertilizers. The mechanisms of inorganic phosphate solubilization by PSM and the mechanisms of organic phosphorus mineralization are highlighted together with some factors that determine the success of this technology. Finally we provide some indications that the use of PSM will promote sustainable agriculture and conclude that this technology is ready for commercial exploitation in various regions worldwide.

Farmer perception of soil erosion and investment in soil conservation measures: emerging evidence from northern Taraba State, Nigeria

AbstractTo combat soil erosion in the northern part of Taraba State, Nigeria, farmers are of major importance. Their perceptions vitally influence the levels of support and investment associated with solving problems of soil erosion through adoption of practices that are alternative to those in current use, including approaches focused on soil conservation. The objective of this study was to evaluate how farmer perceptions of soil erosion influence their investments in soil conservation, particularly soil or stone bunds, their applications of organic amendments and inorganic fertilizers and other soil conservation practices. In the study area, we undertook a field plot experiment and carried out a survey, using open‐ and closed‐ended questions. Water erosion and depletion of fertility were taken as the main indicators of soil erosion. The results of the experiment showed that farmers were aware of and perceived both indicators as having increased over the past decade. Farmer investments in water erosion control (3.7 US$/ha) and the prevention of soil fertility depletion (37.8 US$/ha) in the study area were found to be limited. The results also showed that awareness of water erosion was only marginally correlated with investment in water erosion control (χ2 = 4.906,P = 0.09) and not associated with investments in soil fertility control measures (χ2 = 0.175,P = 0.92). Those farmers who identified depletion of soil fertility as a problem, based on erosion, were not significantly more likely to make greater investments in soil conservation (χ2 = 0.947,P = 0.62) but did invest more in fertility measures (χ2 = 3.199,P = 0.20). Hence, further research is needed to determine other factors that may influence farmer investment in soil conservation, especially factors related to socio‐economic characteristics of farm households, institutional and technological innovations and field characteristics that were not addressed in this study.

The adoption of a portfolio of sustainable agricultural practices by smallholder farmers in Zimbabwe

Climate change and variability and soil fertility depletion are among the main biophysical limiting factors for increasing per capita food production for smallholder farmers in developing countries. To tackle these challenges, the adoption of sustainable agricultural practices (SAPs), has become an important policy topic among donors and development agencies in developing countries. This paper examines the adoption decisions for SAPs, using recent primary data collected in 51 villages in 3 districts of Zimbabwe. The article employs a multivariate probit regression to model simultaneous interdependent adoption decisions by farm households. The analysis reveals that education, farm experience, farm size, income, access to information and agroecology influence the adoption of SAPs. Policies that are aimed at improving household income and enhancing access to information can increase the uptake of SAPs by smallholder farmers. Extension messages should aim to emphasize the complementarities between different SAPs. This information could help policy makers and extension agents to formulate and promote a package of SAPs.