SPATIAL VARIABILITY MAPPING OF SOIL PROPERTIES FOR AGRICULTURAL PURPOSES USING GEOSTATISTICAL TOOLS – A CASE OF M’MINA VILLAGE
Abstract
The scientific assessment of soil involves the analysis of the physical, chemical as well as the biological properties of soil. These kind of assessments differ from the general tradition assessment (where soil quality is assessed by the quality and stand of the crops grown on the soil) in that they take into consideration important scientific facts such as the variability of soil nutrients in space. The information from such analyses is essential in making the right and proper decisions for improved and sustainable agriculture. It was therefore the aim of this study to conduct such an analysis with the objective of determining the spatial variability of the main three macronutrients, NPK.
The study area was M’mina village found in Thyolo which is in the southern region of Malawi. 10 georeferenced soil samples were collected from non-random locations in the area and analyzed at Bvumbwe Research Station to determine their concentrations.
The data was then analyzed using geostatistical tools, semivariogram and Ordinary Kriging and maps classifying the concentrations of these elements were produced. The results showed that N was very low and low in 28% and 72% of the whole area respectively; P varied from low, medium, high and very high in 41%, 27%, 9% and 23% of the whole area respectively and K varied from being very low, low and then medium in 48%, 49%, and 3% of the whole area. Conclusions drawn from these results were that legumes are the most suitable crops for this area followed by other plants like lettuce, cassava and sweet potatoes. For other crops like maize, the application of manure and/or synthetic fertilizers would be required. The study therefore proved significant in guiding decisions of crop selection and input application. It would be recommended that further studies be done and they should include the collection of more samples, analysis of various soil properties and take into consideration other factors that affect agriculture.
Research summary
These kind of assessments differ from the general tradition assessment (where soil quality is assessed by the quality and stand of the crops grown on the soil) in that they take into consideration important scientific facts such as the variability of soil nutrients in space. It was therefore the aim of this study to conduct such an analysis with the objective of determining the spatial variability of the main three macronutrients, NPK. The results showed that N was very low and low in 28% and 72% of the whole area respectively; P varied from low, medium, high and very high in 41%, 27%, 9% and 23% of the whole area respectively and K varied from being very low, low and then medium in 48%, 49%, and 3% of the whole area. It would be recommended that further studies be done and they should include the collection of more samples, analysis of various soil properties and take into consideration other factors that affect agriculture.