Abstract
Application of biochar alters availability of nutrients and acidic cations in soils which in turn could affect growth of plant to different degrees. Effect of rubber wood biochar amendment on the growth and nutritional status of Hevea nursery plants was determined in this study. Biochar were applied at 1% and 2% (w/w) with and without the recommended rates of N and Mg liquid fertilizers (LF). Two control treatments with 0% biochar but with and without recommended levels of all N, P, K, and Mg LF were also included. Application of biochar alone has a significant positive effect on above ground dry matter accumulation of the rootstock seedling (81% over the 0% biochar + no LF control) while no effect on the scion growth. Growth of plants in LF added treatments were much higher. Combining 2% biochar with N and Mg significantly increased the above ground dry matter accumulation over N-P-K-Mg only treatment in both rootstock seedling (29%) and the scion (61%). Biochar only application did not affect the N and P and decreased K and Ca concentrations in leaves. When combined with N and Mg fertilizers however, biochar significantly increased total N, P, Mg and Ca uptake. Biochar only application (2%) significantly decreased the leaf Mn concentrations in the seedling probably due to decrease in Mn availability as a result of increase in soil pH. The increase in soil pH due to biochar addition decreased with time close to original values in soils that received LF, possibly due to sulfate of ammonia. We concluded that application of rubber wood biochar (upto 2% w/w) could improve the growth of Hevea plants with the use of only N and Mg fertilizers under nursery conditions tested in this experiment.
Highlights
Rubber [Hevea brasililiensis L. (Willd. ex Adr. de Juss.) Müell
Growth of root stock seedling Application of biochar without liquid fertilizers (LF) did not affect the leaf dry matter content compared to the 0% biochar-no LF control (Table 2)
When the biochar rate was increased up to 2% without LF, a significant increase in the stem dry matter (5.8 g plant-1) as well as total shoot dry matter (9.4 g plant-1) could be observed compared to the 2.8 and 5.2 g plant-1, respectively of the 0% biochar-no LF control
Summary
Arg.], a native tree spp. in the Amazon basin, was domesticated as a plantation crop in the south and southeast Asian countries during the latter part of the 1870’s. This commercially and environmentally important plantation crop has been spread over 10.3 million hectares globally and it is dominated by the Asian region with 93% of the extent (International Rubber Study Group 2012). In the tropical Asian countries, rubber is grown on highly weathered soils characterized by very low organic C contents (Zhang et al 2007) due to intensive cultivation over 100 years. Investigations on Terra Preta de Indio soils in the Amazon forest (Glaser et al 2001; Lehmann et al 2003; Liang et al 2006), from where rubber plants were brought to the Asian continent, suggest that repeated applications of charcoal over a period of time could increase fertility in soils compared to those in non-charcoal added soils and the effects could be long lasting
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