Spatial variability of bulk soil electrical conductivity in a Malaysian paddy field: key to soil management

On-the-go EC sensor is a useful tool in mapping the apparent soil electrical conductivity (EC_a) to identify areas of contrasting soil properties. In non-saline soils, EC_a is a substitute measurement for soil texture. It is directly related to both water holding capacity and cation exchange capacity (CEC), which are key ingredients of productivity. This sensor measures the EC_a across a field quickly and gives detailed soil features (1-s interval) with few operators. Hence, a dense sampling is possible and therefore a high resolution EC_a map can be produced. This paper presents experiences in acquiring detailed EC_a information that is correlated to other soil properties for precision farming of rice. The study was conducted on a 9 ha rice plot in MARDI Seberang Prai Station, Penang. The VerisEC3100 was pulled across the field in a series of parallel transects spaced about 15 m apart. The study showed that shallow and deep EC_a had high correlation and shallow EC_a had significant correlation to P. Deep EC_a had significant correlation to P, K and yield. Regression equations showed that N and P could be estimated by shallow EC_a but, pH, K and yield were better estimated by deep EC_a. This study was able to draw some basic ideas of nutrient zone management according to precision farming technique.