Soil characteristics under cash crop farming in upland areas of Sarawak, Malaysia

Abstract

This study discusses soil fertility under perennial cash crop farming (para rubber, Hevea brasiliensis; black pepper, Piper nigrum; oil palm, Elaeis guineensis) conducted by local farmers and an oil palm estate in an upland area of Sarawak, Malaysia, in comparison with the surrounding secondary forests. In the farmlands of the local farmers, rubber farming was conducted without fertilizer application, while 2 to 5 t ha-1 of NPK compounds were applied annually on pepper farms. Soils under rubber farming were acidic with poor nutrient contents, resembling soils in secondary forests. In pepper farms, soils were less acidic and showed high nutrient contents, especially with respect to available P and exchangeable Ca. This trend became stronger with increasing farming duration. Fertilizers applied around pepper vines appeared to migrate and spread across the fields. Bulk density and hardness of surface soils were higher in pepper farms than in secondary forests, indicating soil compaction due to field works. In the oil palm estate, annual fertilizer application rates were moderate at 0.4 to 0.8 t ha-1 of NPK compound fertilizers. However, the soil properties in the oil palm estate were similar to those of the small-scale pepper farms. Close to the bases of the palms where fertilizers usually are applied, the contents of exchangeable Ca and available P were high. Nutrient uptake by the dense root systems of the palms seemed to prevent excessive loss of nutrients through leaching. Loss of soil organic matter and deterioration of soil physical properties were brought about by terrace bench construction, but the soils seemed to recover to some extent over time. In conclusion, technologies such as intercropping and the appropriate allocation of different crops 2 to specific locations as well as the proper selection and dosage of fertilizers should be developed and adopted to improve fertilizer efficiency and prevent water pollution due to fertilizer wash-off from farmlands.

Characteristics of the contrasting soils on Kahayan River banks in Central Kalimantan, Indonesia

“…High correlations of clay contents were found with pH, CEC, ECEC, and exchangeable Al ( Table 5), indicating that clay content is a determinant factor for soil acidity and cation retention capacity of soils. In contrast, T-C contents at the 0-10 cm layer were not correlated with clay contents, CEC or ECEC across all of the study sites nor within each land uses although the previous studies reported significant correlation between clay and T-C contents and between the T-C contents and CEC or ECEC in the surface soils (Ohta and Effendi 1992b, Ohta et al 1993, Tanaka et al 2007, 2009). Relatively clay-rich soils including the four PLF soils were distributed in the belt perpendicular to Kahayan River.…”

“…The levels of T-C and T-N both at the 0-10 cm and 30-40 cm layers were also similar to or higher than those not only reported in these studies but also those under secondary forest and farmlands (Kleinman et al 1996, Lawrence et al 2001, Tanaka et al 2007, 2009). The C/N ratios were 13.1 on average across the study sites and lower than the values of more than 15 reported in the most of these previous studies.…”

“…The properties at PSF and PR sites did not differ from each other and were intermediate between PC and PLF sites in spite of the result of the interview that the villagers preferentially selected the lands where rice growth was better for rubber planting. Tanaka et al (2009) also reported almost identical soil properties of rubber garden and fallow forests.…”

“…Looking over Borneo, together with vast numbers of forest science studies, previous studies from soil science have been centered mainly on sloping areas, where the original vegetation is dipterocarp forest and the soils are Ultisols or Inceptisols; for example, Ohta and Effendi (1992a, b), Ohta et al (1993), and Hirai et al (1997) for soils under dipterocarp forests and Kleinman et al (1996), Lawrence et al (2001), Kendawang et al (2004Kendawang et al ( , 2005, Tanaka et al (2004, 2009), and de Neergaard et al (2008 for soils under farming practices or fallow forests.…”

Effects of Depth and Land Cover on Soil Properties as Indicated by Carbon and Nitrogen-Stable Isotope Analysis

“…Further, studies have demonstrated that the loss of organic matter through the conversion of forest to plantation results in higher Bd values [38]. In addition, the high Bd values are an indicator of soil compaction in plantations [39].…”