Soil Water Content Below 33.7% Progressively Reduces the Latex Yield of Rubber PB 60, A Study in Sembawa, South Sumatra, Indonesia

Abstract


 
 
 Rubber is one of the economically important tropical trees that produces natural rubber, an essential industrial raw material in Indonesia. In general, rubber can grow well in areas with 1,500 - 3,000 mm rainfall per year that evenly distributed round the year. During the dry season, water availability is reduced so that water becomes a limiting factor for the growth and production of the rubber tree. This paper aimed to determine minimum soil water content that must be maintained to prevent the reduction of PB 260 rubber production based on field water balance. This research was carried out at the Indonesian Rubber Research Institute Experimental Field, South Sumatra, Indonesia, between 2014 to 2019. This experiment used PB 260 clone which was planted in 2001 using a 6 x 3 m plant spacing. Soil analysis showed that the Sembawa had a clay loam soil texture. The measured parameters were latex production (kg per ha per year), rainfall, and evapotranspiration (mm). The results from our six years of study showed that rubber production always decreased when soil water content started to decline below field capacity (33.7 %, or equal to 337 mm with 1m depth of root zone).
 
 

Prediction of Rubber Yield Based on Soil Water Content

“…On the contrary, the highest rubber yield was generated in the same month with the highest soil water content (May). This finding was in accordance with previous research which reported that the occurrence of dry season resulted in decrease of soil water content as well as rubber yield [2,7,19]. Furthermore, the same pattern of the fluctuation of soil water content and rubber yield indicated that rubber yield can be predicted using soil water content data.…”

“…However, in some areas in Indonesia, the rainfall is not evenly distributed, hence drought usually occurs several months in a year. The drought causes a decrease in rubber yield [2,3]. However excessive water in the rubber field also decreases rubber yield, because the root zone is inundated by waterlogging [4].…”

Climate Influences on Latex Yield in South Sumatra, Indonesia

“…This consequently led to heightened rubber growth, elevated latex yields, and improved quality of the latex yield. Ardika and Cahyo (2020), identified a positive correlation between rainfall and the production of the PB 260 rubber clone, 0.89 0.03 tn Note: ** significant correlation at the 0.01 level; * significant at the 0.05 level; and tn the correlation is not significant spanning from one to 3-month lead time. Study showed that latex yield increased during the rainy season under irrigation as reported from a field experimental plot in Thailand (Mak et al, 2008).…”

“…In the wet zone area of Sri Lanka, a reduction in rainfall produced rubber yield, which was 35% lower compared to normal climate condition (Alahacoon and Giriraj, 2022). In dry months, rubber plants experience high temperatures and insufficient rainfall causing moisture stress, which is the limiting factor for maximum latex yield (Kunjet et al, 2013;Ardika and Cahyo 2020). Moisture depletion was associated to reduced growth and latex yield (Raj et al, 2005).…”