Soil Fertility Information Research Articles

Determinants of Simultaneous Use of Soil Fertility Information Sources among Smallholder Farmers in the Central Highlands of Kenya

Soil fertility decline is a significant drawback to food and nutritional security in sub-Saharan Africa. However, information and knowledge barriers seriously impede the adoption, effective use, and scaling up of soil fertility management innovations, especially by smallholder farmers who produce the bulk of the region’s food needs. Apart from the knowledge that smallholder farmers seek soil fertility information from diverse sources, which they apply simultaneously, there is limited knowledge of farmers’ information-seeking behaviour regarding which sources are used simultaneously and the factors influencing these choices. We employed a cross-sectional survey study design to determine the simultaneous use of soil fertility information sources of 400 smallholder farming households in the Central Highlands of Kenya. We analysed the data using descriptive statistics, principal component analysis (PCA), and a multivariate probit model. The PCA distinguished seven categories of information sources farmers use: local interpersonal, cosmopolite interpersonal, aggregative, print/demonstration, broadcast media, community-based, and progressive learning sources. The intensity of use revealed that most of the smallholders used soil fertility information sources simultaneously and primarily as complements. The determinants of simultaneous use of soil fertility information sources were farmer location, marital status, main occupation, age, farming experience, exposure to agricultural training, group membership, arable land and livestock units owned, soil fertility status, soil fertility change, and soil testing. This study’s findings have implications for information dissemination strategies involving using multiple complementary sources of knowledge for improved soil health and productivity.

Determinants of Soil Fertility Information Needs and Access Among Smallholder Farmers in the Central Highlands of Kenya

ABSTRACT Soil fertility decline is a significant challenge to the agroecosystems in sub-Saharan Africa (SSA). Accurate and demand-driven soil fertility information is vital for improving agricultural production. We achieved two objectives, i) identifying soil fertility information needs and access and ii) assessing socioeconomic determinants of soil fertility information needs and access among smallholder farmers in the central highlands of Kenya. We sampled 397 smallholder farming households in Murang’a and Tharaka-Nithi counties. We found high soil fertility information need indices among farmers in the two regions. The main soil fertility information needs for farmers in Murang’a County were knowing the correct method of manure application, knowing sources of information, and how to determine soil fertility levels. In Tharaka-Nithi County, farmers’ information priorities were how to apply conservation agriculture, knowing soil erosion control methods, and how to apply animal manure. We found mixed results on soil fertility information access ranging from low to high across different information items and study sites. The binary logistic regression results highlight the influence of farmer perceptions and other factors on soil fertility information need and access. To promote soil fertility information access, agricultural policies should consider site-specific information priorities and socioeconomic contexts.

Digital Mapping of Soil Profile Properties for Precision Agriculture in Developing Countries

The soil profile and its spatial distribution are two essential aspects for promoting sustainable agriculture, with precise inputs in quantity, space, and time. This work’s objective was to elaborate a digital map of soil fertility considering the complete profile for the accurate management of amendments and fertilizers. For the preparation of the soil fertility map, the following inputs were used: a digital elevation model, information from 44 soil profiles, the conversion of the properties of the soil profiles into surface units, geostatistical analysis of the soil properties, and the preparation of the final map with a geographic information system. The best spatial models were achieved with CEC, pH, Ca, Mg, Na, and K. The map of the soil fertility classes was produced considering CEC and the pH value. The soil fertility classes presented the following sequence of occupied surfaces: very low, medium, very high, high, and low. A process was generated to elaborate digital maps (geostatistics) of soil fertility using taxonomic information from soil profiles and considering the complete profile. The process converts soil classification into geographic and soil fertility information from basic science to application.

English

The potato is one of the most important food and cash crops in Malawi, but current yields are low and the fertilizer recommendations rely on outdated soil fertility information. To understand the influence of soil factors in limiting current potato production, the mineralogical and physicochemical soil characteristics of 26 farms in the central highlands of Malawi were evaluated. Cluster analysis with clay, crystalline iron oxide, and total carbon content revealed three clusters with two corresponding to Ferralsols and one to Regosols, which are known to exist in the area. In the three clusters, the soil was generally acidic with low exchangeable acidity and aluminium (Al; < 0.7 cmolc kg-1); thus, Al toxicity was not a concern because the soil solution Al would be very low to negatively affect plant growth. Inorganic nitrogen was adequate, while available phosphate and exchangeable potassium (K) were variable within each cluster. However, a deficiency in exchangeable calcium (Ca; < 3.6 cmolc kg-1) and magnesium (Mg; < 1.2 cmolc kg-1) indicated that low base cation concentration was the problem and the potential yield-limiting factor. Soil management, not soil type, appeared to determine soil nutrient conditions based on the current soil Ca and Mg deficiencies and variable K nutrient status. There is a need for updating the current fertilizer recommendations by incorporating K, Ca, and Mg and promoting soil amendment interventions using locally available animal manure and plant ash. Key words: acid soil; fertilizer; Ferralsols, Regosols, Solanum tuberosum L., aluminium toxicity, calcium; magnesium.

Uptake of integrated soil fertility management technologies in heterogeneous smallholder farms in sub-humid tropics

Low soil fertility strongly affects environmental sustainability and Sustainable Development Goals (SDGs) worldwide. Integrated soil fertility management (ISFM) is a potential remedy for declining soil fertility. We addressed determinants of ISFM technologies and identified the sources of soil fertility information using cluster and ordered probit analyses in two counties of the Central Highlands of Kenya. In Tharaka-Nithi county, the uptake of ISFMclass1 (Animal manure +anti-erosion + inorganic fertilizer +crop rotation + legume intercrop), positively correlated with membership to cooperatives, religious groups, SACCOs, and ownership of wheelbarrow but negatively associated with gender, level of education, low farming experience and increased off-farm income. The uptake of ISFMclass2 (Compost +Tithonia diversifolia +minimum tillage +agroforestry + crop residue retention) significantly correlated with religious group membership and ownership of radio. The uptake of ISFMclass3 (sole green manure) positively correlated with a household with an adult offering outside labor but negatively associated with distance to agro-dealers. In Murang'a, ISFMclass2 (Animal manure +inorganic fertilizer +anti-erosion + legume intercrop) is positively associated with farmers' age, membership to cooperatives, television ownership, and access to handhoe and distance to tarmacked roads. Access to drought power, distance to tarmacked road, and buyers positively correlated with ISFMclass1 (Agroforestry +green manure +minimum tillage +crop residue retention + crop rotation). There was a positive correlation between access to drought power and uptake of ISFMclass3 that combined compost and Tithonia diversifolia. We conclude that the region's uptake of unique ISFM combinations is influenced by socioeconomic, bio-physical determinants, and farmers' perception of soil fertility status. We thus recommend that increased upscaling of uptake of unique combinations of ISFM technologies require robust collaboration among various local development stakeholders to address the prohibitive factors while strengthening enabling ones.

Soil fertility constraints and management to increase crop yields in the dryland farming systems of Aceh, Indonesia

In Aceh, Indonesia, low dryland crop yields entrench rural poverty. The lack of soil fertility information hinders the development of soil management programs to assist farmers to increase crop yield. This study identified soil-based constraints to production and management options to increase crop yield. We analysed 254 soil samples from 127 dryland cropping sites across Pidie, Bireuen, Aceh Besar and Aceh Barat districts for pH, soil organic carbon (SOC), total nitrogen (N), phosphorus (P), base saturation (BS) and cation exchange capacity (CEC). The dominant soils were Entisols, Inceptisols and Ultisols, with some Andisols and Mollisols. Overall, the CEC range was 10–60 cmol(+) kg–1 and available P was 0.5–702 mg kg–1 but most had poor fertility: SOC < 20.0 g kg–1, total N < 2.0 g kg–1, low basic cations and BS < 40%. The Ultisols and some Entisols and Inceptisols were acidic, with aluminium saturation >20% and available P < 6.5 mg kg–1. To sustainably increase crop yield, we concluded that these soils need lime where acidic, fertilisers for nutrients and stable carbon-rich amendments for system stability. This dataset will guide future agricultural research and development programs in Aceh to improve farmer practices and food security.

Green methodology for soil organic matter analysis using a national near infrared spectral library in tandem with learning machine

Precision agriculture requires faster and automatic responses for fertility parameters, especially regarding soil organic matter (SOM). In Brazil, the standard methodology for SOM determination is a wet procedure based on the oxidation of the sample by an excess of potassium dichromate based on Walkley–Black method. This methodology has serious drawbacks, since, at a national level, generates approximately 600,000 L/year of toxic acid waste containing Cr3+ and possibly Cr6+, besides time consuming and expensive. Herein, we present a faster green methodology that can eliminate the generation of these hazardous wastes and reduces the costs of analysis by approximately 80%, democratizing the soil fertility information and increasing the productivity. The methodology is based on the use of a national near infrared spectral library with approximately 43,000 samples and learning machine data analysis based on a random forest algorithm. The methodology was validated by submitting the prediction results of 12 blind soil samples to a proficiency assay used for fertility soil laboratories qualification, receiving the maximum quality excellence index, indicating that it is suitable for use in routine analysis.

Spatial variability of soil fertility in an integrated crop livestock forest system

Knowledge on spatial variability of soil properties is useful for the rational use of inputs, as in the site specific application of lime and fertilizer. Crop-livestock-forest integrated systems (CLFIS) provide a strategy of sustainable agricultural production which integrates annual crops, trees and livestock activities on a same area and in the same season. Since the lime and fertilizer are key factors for the intensification of agricultural systems in acid-soil in the tropics, precision agriculture (PA) is the tool to improve the efficiency of use of these issues. The objective of this research was to map and evaluate the spatial variability of soil properties, liming and fertilizer need of a CLFIS. The field study was carried out in a 30 ha area at Embrapa Pecuária Sudeste in São Carlos, SP, Brazil. Soil samples were collected at 0–0.2 m depth, and each sample represented a paddock. The spatial variability of soil properties and site-specific liming and fertilizer needs were modeled using semi-variograms, the soil fertility information were modeled. Spatial variability soil properties and site specific liming and fertilizer need were modeled by kriging and inverse distance weighting (IDW) techniques. Another approach used was based on lime and fertilizer recommendation considering the paddocks as the minimum management unit. The results showed that geostatistics and GIS were useful tools for revealing soil spatial variability and supporting management strategies. Soil nutrients were used to classify the soil spatial distribution map and design site-specific lime and fertilizer application zones. Spatial analyses of crop needs and requirement can provide management tools for avoiding potential environmental problems, caused by unbalanced nutrient supplies.

Spatial variability of soil properties and yield of a grazed alfalfa pasture in Brazil

Knowledge of the spatial variability of soil properties and of forage yield is needed for informed use of soil inputs such as variable rate technology (VRT) for lime and fertilizers. The objective of this research was to map and evaluate the spatial variability of soil properties, yield, lime and fertilizer needs and economic return of an alfalfa pasture. The study was conducted in a 5.3 ha irrigated alfalfa pasture in Sao Carlos, SP, Brazil that was directly grazed and intensively managed in a 270-paddock rotational system. Alfalfa shoot dry matter yield was evaluated before grazing. Soil samples were collected at 0–0.2 m depth, and each sample represented a group of 2 or 3 paddocks. Apparent soil electrical conductivity (ECa) was measured with a contact sensor. The cost of producing 1 ha of alfalfa was estimated from the amount of lime and fertilizer needed and was then used to estimate the total cost of production for the dairy system. The alfalfa dry matter yield was used to simulate the pasture stocking rate, milk yield, gross revenue and net profit. The spatial variability of soil properties and site-specific liming and fertilizer needs were modeled using semi-variograms with VESPER software, the soil fertility information and economic return were modeled with SPRING software. The results showed that geostatistics and GIS were effective tools for revealing soil and pasture spatial variability and supporting management strategies. Soil nutrients were used to classify the soil spatial distribution map and design site-specific lime and fertilizer application maps. Spatial variation in forage and spatial estimates of stocking and milk yield are adequate pasture management tools. Spatial analyses of needs, forage availability and economic return are management tools for avoiding economic problems, as well as potential environmental problems, caused by unbalanced nutrient supplies and over- or under-grazing.

County Soil Fertility Information Management System Based on Embedded GIS

Almost all existing soil fertility management information systems run on PC with a poor mobility, which can not be used directly in the fields. This paper proposed a method using the embedded GIS technology, embedded database technology and soil nutrient balance model, to develop soil fertility management information system of Jianshui County in Yunnan Province, China. This system could run on Windows mobile 6.5 phones, PDA and other smart terminal devices. Functions of the system included viewing soil fertility information, getting fertilization formula, etc. The application of the system was good, which could guide farmers to fertilize more rationally and also help governor to develop agricultural policy.

Linking spatio-temporal variation of crop response with sediment deposition along paddy rice terraces

In tropical mountainous regions of South East Asia, intensive cultivation of annual crops on steep slopes makes the area prone to erosion resulting in decreasing soil fertility. Sediment deposition in the valleys, however, can enhance soil fertility, depending on the quality of the sediments, and influence crop productivity. The aim of the study was to assess (i) the spatio-temporal variation in grain yield along two rice terrace cascades in the uplands of northern Viet Nam, (ii) possible linkage of sediment deposition with the observed variation in grain yield, and (iii) whether spatial variation in soil water or nitrogen availability influenced the obtained yields masking the effect of inherent soil fertility using carbon isotope (13C) discrimination and 15N natural abundance techniques. In order to evaluate the impact of seasonal conditions, fertilizer use and sediment quality on rice performance, 15N and 13C stable isotope compositions of rice leaves and grains taken after harvest were examined and combined with soil fertility information and rice performance using multivariate statistics. The observed grain yields for the non-fertilized fields, averaged over both cascades, accounted for 4.0±1.4Mgha−1 and 6.6±2.5Mgha−1 in the spring and summer crop, respectively, while for the fertilized fields, grain yields of 6.5±2.1Mgha−1 and 6.9±2.1Mgha−1 were obtained. In general, the spatial variation of rice grain yield was strongly and significantly linked to sediment induced soil fertility and textural changes, such as soil organic carbon (r 0.34/0.77 for Cascades 1 and 2, respectively) and sand fraction (r −0.88/−0.34). However, the observed seasonal alteration in topsoil quality, due to sediment deposition over two cropping cycles, was not sufficient to fully account for spatial variability in rice productivity. Spatial variability in soil water availability, assessed through 13C discrimination, was mainly present in the spring crop and was linearly related to the distance from the irrigation channel, and overshadowed in Cascade 2 the expected yield trends based on sediment deposition. Although δ15N signatures in plants indicated sufficient N uptake, grain yields were not found to be always significantly influenced by fertilizer application. These results showed the importance of integrating sediment enrichment in paddy fields within soil fertility analysis. Furthermore, where the effect of inherent soil fertility on rice productivity is masked by soil water or nitrogen availability, the use of 13C and 15N stable isotopes and its integration with conventional techniques showed potential to enhance the understanding of the influence of erosion – sedimentation and nutrient fluxes on crop productivity, at toposequence level.

Iodine Distribution in the Environment as a Limiting Factor for Roe Deer Antler Development

The iodine-containing hormones produced by the thyroid gland play a role in the complex neuro-hormonal regulation of antler development. The proper function of the thyroid depends on the adequate iodine supply of the organism, which is directly related to the iodine content of food and drinking water. The purpose of this study was to explore the connection between the iodine content of the water base, which has a strong correlation with the iodine concentration of environmental components available to animals, and the antler weight of roe deer (Capreolus capreolus) shot in Hungarian hunting areas. Using a general linear model, controlling for the collective effects of other environmental factors (deer population density, harvest rate, land use, and soil fertility information), the iodine content of the water base explained 51.4% of the total variance of antler weights. The results suggest that antler weights increase with increasing iodine concentration regardless of other factors; thus, the environmental iodine distribution can be a limiting factor suppressing roe deer performance assessed here as antler weight. Further experimental studies of controlled iodine uptake are needed to define the exact physiological iodine requirements of roe deer bucks.

Mycomedicine and Ethnomycology: The Nigerian Experience

There is a dearth of information in the scientific literature on the indigenous uses of mushrooms in Nigeria. There is also a poor documentation of ethnoknowledge among our people, which is still contributing to a loss of vital information, on almost a daily basis. This paper, therefore, sheds light on the current status of mycomedicine and ethnomycololgy of mushrooms in Nigeria. It also emphasizes the need for documenting indigenous knowledge and the empirical confirmation of our local people’s claims about the therapeutic effects of mushrooms in our environment. The authors stress the need for progress in mycomedicine if serious attention is given to eliciting the vital information from rural community dwellers, where reliance on natural materials for treatment of ailments is still much observed.Pertinent questions that may reveal the relevance of ethnomycology include: How fast can we progress in mycomedicine without ethnomycology? How much has ethnomycology contributed to the present status of mycomedicine? How do we gather basic information on medicinal mushrooms? Is it not more cost-effective to seek indigenous knowledge on the uses of mushrooms, along with the legends with which they are associated (ethnomycology), than to study the medicinal relevance of all the mushrooms in the wild?Mycological concepts and their applications are also much observed in Nigerian cultures. Many proverbs and other sayings involve mushrooms and show age-long interactions with mushrooms. Documentation of ethnomycological and ethnomycomedicinal information is being advocated to encompass all the fungi used in one way or another by a particular culture.Another aspect of this presentation includes soil fertility information, based on the ethnoknowledge of a particular tribe in Nigeria, and how this can be used to educate the custodians of this knowledge on soil fertility involving mushrooms. Ethnoknowledge among the diverse Nigerian cultures also includes the use of fungi in food and drink fermentation. Notable among such foods are “yan olude” from maize grains, “pito” from the grains of Sorghum bicolor, and “shekete” from plantain (Musa parasidiaca). Out of the three fermented products, the one that involves direct use of culture of organisms is pito. Much effort is being made to preserve the culture at different stages of the preparation of the drink. It is also important to note that some of the ethnomycological practices cannot be explained by science, while quite a number of them can be confirmed and improved upon in the laboratory.In addition, many precautions observed by the indigenous people can certainly be explained by science. A good reference point is the observation by the indigenous cultures in southern Nigeria that fermented drinks would “spoil” if exposed to orange fruits or even to the peels. Orange peels are usually kept at quite an appreciable distance from such fermented drinks, during and after preparation.

Relationships between soil bulk electrical conductivity and the principal component analysis of topography and soil fertility values

Measures of soil electrical conductivity (EC) and elevation are relatively inexpensive to collect and result in dense data sets which allow for mapping with limited interpolation. Conversely, soil fertility information is expensive to collect so that relatively few samples are taken and mapping requires extensive interpolation with large estimation errors, resulting in limited usefulness for site-specific applications in precision agriculture. Principal component (PC) analysis and cokriging can be applied to create meaningful field scale summaries of groups of attributes and to decrease the estimation error of maps of the summarized attributes. Deep (0–90 cm) and shallow (0–30 cm) EC, elevation, and soil fertility attributes were measured in fields under corn (Zea mays L.) and soybean (Glycine max L.) rotations, at two sites in Illinois (IL) and two sites in Missouri (MO). Soil fertility and topography attributes were summarized by PC analysis. The first topography PC (TopoPC1) contrasted flow accumulation against elevation and curvature, to describe the main topographic pattern of the fields. The first soil fertility PC (SoilPC1) consistently grouped together cation exchange capacity (CEC), Ca, Mg, and organic matter (OM). SoilPC1 was well correlated to soil EC for all sites and cokriging with EC had higher r 2 in the crossvariogram models compared to ordinary kriging. The second and third soil fertility PCs (SoilPC2 and SoilPC3) were concerned with soil pH and P, and reflected historic land use patterns. Maps of SoilPC2 and SoilPC3 had little relationship to soil EC or topography and so could not be improved by cokriging. Abbreviations: CEC – cation exchange capacity; EC – soil bulk electrical conductivity; OM – soil organic matter; PC – principal component; SoilPC – soil fertility principal component; Sph – spherical variogram function; TopoPC – topography principal component.

Sewage Biosolids Cumulative Effects on Extractable‐Soil and Grain Elemental Concentrations

AbstractWhile land application of sewage biosolids is the most expedient method of recycling plant nutrients, concern over trace element additions resulted in U.S. Environmental Protection Agency (USEPA) beneficial‐use regulations. We studied 11‐yr biosolids addition effects on ammonium bicarbonate diethylenetriaminepentaacetic acid (AB‐DTPA) and 4 M HNO3 extractable levels of soil Cd, Cu, Mo, Ni, P, Pb, and Zn, and the relationship between the soil‐extractable concentrations and grain concentrations. The soils at our four dryland wheat (Triticum aestivum L.) sites were Aridic Paleustolls (Weld and Platner loam). For each application, we used four rates of biosolids (0, 7, 14, and 28 Mg ha−1) from the Littleton/Englewood, CO Wastewater Treatment Plant. We tested linear, quadratic, and either exponential‐rise (plateau) or exponential‐decay models for AB‐DTPA‐ and 4 M HNO3‐extractable concentrations compared with the cumulative quantity of biosolids‐borne element added and with elemental grain concentrations. Models for AB‐DTPA‐extractable Cu, P, Pb, and Zn and 4 M HNO3‐extractable Cu and P vs. the cumulative quantity added produced R2 values ≥ 0.46. For grain concentrations, only the models for AB‐DTPA vs. grain Zn produced an R2 ≥ 0.50. For monitoring soil levels of Cd, Cu, Mo, Ni, P, Pb, and Zn in Paleustolls (common soils in the western Great Plains dryland wheat areas) that continuously receive biosolids, we recommend AB‐DTPA over 4 M HNO3 soil extractions. The AB‐DTPA extractions also provide soil fertility information (NO3‐N and plant available P, K, and micronutrients).

COMPARATIVE POTASSIUM LEVELS REMOVED FROM SOILS BY ELECTRO-ULTRAFILTRATION AND SOME CHEMICAL EXTRACTANTS

The objective of this study was to compare extractable potassium levels removed from soils by electro-ultrafiltration (EUF) and by conventional chemical soil tests. Accordingly, concentrations of potassium removed from soils by three EUF and six chemical extraction procedures were compared, on a group of 50 soils which contained less than 20% clay and on a second group of 52 soils which contained from 20 to 50% clay, by means of regression and correlation techniques. The following three EUF extraction procedures were tested: (i) 50 V at 5-min; (ii) 50 V at 5-min plus 200 V at 25-min; and (iii) 300 V at 15-min. Results indicated that the concentrations of soil K found in the combined anolyte and catholyte of the EUF or removed by the chemical procedures were very closely related (r-values generally greater than 0.90). However, EUF was less efficient in removing K from soils containing higher proportions of clay than NH4OAc, the new Mehlich solution, or the double acid mixture used at 1:30 wt/vol soil-solution ratio. As soil K fractions extracted by different EUF procedures were closely related among themselves as well as between the chemical methods tested, EUF would not provide soil fertility information that could not be obtained by less laborious and expensive chemical procedures. Key words: Soil testing, NH4OAc, double acid, new Mehlich extractant, electro-ultrafiltration