Cations ratio and its relationship with other soil nutrients of Java intensified lowland rice

Abstract

The soil cation ratio is the result of the interaction of various factors, including soil acidity, organic C content, clay minerals, and cultivation management. This paper aims were to study the cation ratio in lowland rice in Java and its relationship with the other nutrients. Soil chemical data were collected from survey for soil maps, soil nutrient status maps, and previously published data. The results showed that the average of cation saturation ratio in lowland rice in Java was 70.8:24.5:1.5 for Ca:Mg:K. The Ca, Mg, K, and Na nutrient contents vary by provinces, and there is a high content of Ca, especially in those soils derived from the calcareous parent materials. This high Ca of >50.0 cmol(+) kg−1 has noticed in Grobogan, Bojonegoro, and Gunung Kidul regencies. The domination of Ca cations in the soil can be seen when the Ca saturation >70%, spreading in 36 districts. Ca saturation is positively correlated with pH, P-Bray, and CEC, and negatively correlated with organic C, N-total, Mg, K, and Na saturation. Based on the regression there is a significant negative relationship between Ca and Mg saturations with R2 = 0.92 and a weak negative relationship between K and Na saturations.