Sustainability of black pepper production: A critical analysis of physicochemical soil parameters concerning variables in pepper fields of south India

Abstract

India, the center of origin and the country with the largest area of black pepper cultivation in the world has a low crop productivity in general. Furthermore, Kerala, the traditional black pepper region of India with the broadest crop area, is also one of the low crop productivity zones in the country. Therefore, a critical analysis of the cause of low black pepper productivity in Kerala was hypothesized to be crucial in analyzing the problems of pepper productivity globally. Accordingly, a random survey of the current diversity of the crop and the crop cultivated soil types of two different black pepper cultivation zones in the state was carried out. A critical analysis of the physicochemical soil parameters concerning natural variabilities such as agroclimatic zones, black pepper varieties, soil types, mode of cultivation, and black pepper-cultivated fields in two seasons was the crucial part of the study. The physicochemical soil parameters measured were field water content (FWC), soil pH, total organic carbon (TOC), soil available nitrogen (SAN), soil available phosphorous (SAP), and soil available potassium (SAK). The random survey revealed that 29 black pepper varieties are most intensively cultivated in the region over two main soil orders, Ultisols and Inceptisols, which included 13 soil series. The black pepper varieties commonly cultivated in the region are Karimunda (traditional cultivar) and Panniyur 1 (improved variety). The latter, the most widely cultivated variety in the region, showed the broadest amplitude to soil parameters such as FWC, TOC, SAN, SAP, and SAK. In general, most of the black pepper-growing fields of the region showed an acidic pH, high TOC, low SAN, high SAP, and moderate SAK with significant seasonal fluctuations. As a model study, it enabled us to trace the reasons for the low productivity of black pepper in Kerala. Overall, the study was fruitful in generating significant soil-related and other data concerning black pepper production, which will be beneficial to black pepper farming worldwide.