Paddy soil properties and yield characteristics based on apparent electrical conductivity zone delineation for a humid tropical rice farm

Abstract

The traditional grid soil sampling is laborious and time-consuming. It leads to delay in applying the precision-farming cycle. An apparent electrical conductivity (ECa) sensor (VerisEC 3100) was introduced to delineate zones of contrasting areas of paddy soils for site-specific fertilizer management. This study was conducted to zone the area by ECa data as a summary indicator for zoning paddy soils to facilitate fertilizer management. The area was 145 ha lowland paddy fields in Selangor Malaysia. In a typical plot size of 1.2 ha, the ECa sensor was pulled by a tractor to collect ECa data in 4 passes spaced 15 m apart. Soil samples were collected at 2 points per plot on the track within the area. Under shallow ECa zoning characteristics, zone 1 has significantly lower organic matter (OM), organic carbon (OC), total S, cation exchange capacity (CEC), Mg, Fe and Clay, and has higher exchangeable sodium percentage (ESP), fine sand and sand. Deep ECa zone showed that mean soil base saturation (BS) in zone 3 was significantly higher than those in the other zones while EC was significantly lower. Mean soil P, Mg, total basic cation and clay within zones 1 and 2 were significantly lower as compared to the other zones. However, yield as responded to ECa was found to be in a non-linear form. The results of zonal characterizations indicate that the ECa sensor can provide useful information for zone management practice. Key words: Rice soils, management zones, precision farming, regression, correlation.