No abstract

Abstract. In response to human population increase, the utilization of acid sulfate soils for rice cultivation is one option for increasing production. The main problems associated with such soils are their low pH values and their associated high content of exchangeable Al, which could be detrimental to crop growth. The application of soil amendments is one approach for mitigating this problem, and calcium silicate is an alternative soil amendment that could be used. Therefore, the main objective of this study was to ameliorate soil acidity in rice-cropped soil. The secondary objective was to study the effects of calcium silicate amendment on soil acidity, exchangeable Al, exchangeable Ca, and Si content. The soil was treated with 0, 1, 2, and 3 Mg ha −1 of calcium silicate under submerged conditions and the soil treatments were sampled every 30 days throughout an incubation period of 120 days. Application of calcium silicate induced a positive effect on soil pH and exchangeable Al; soil pH increased from 2.9 (initial) to 3.5, while exchangeable Al was reduced from 4.26 (initial) to 0.82 cmol c kg −1 . Furthermore, the exchangeable Ca and Si contents increased from 1.68 (initial) to 4.94 cmol c kg −1 and from 21.21 (initial) to 81.71 mg kg −1 , respectively. Therefore, it was noted that calcium silicate was effective at alleviating Al toxicity in acid sulfate, rice-cropped soil, yielding values below the critical level of 2 cmol c kg −1 . In addition, application of calcium silicate showed an ameliorative effect as it increased soil pH and supplied substantial amounts of Ca and Si.

This study is a comparison of the litterfall, litter decomposition, soil macrofauna, and nutrient contents in rubber monoculture and rubber-based agroforestry plantations. The three intra-couple differences examined are rubber with pakliang (RP) compared with rubber monoculture (RMP), rubber with timber (RT) compared with rubber monoculture (RMT) and rubber with fruit (RF) compared with rubber monoculture (RMF). Rubber plantation systems were selected at 3 plantations located in nearest pairs at 18 plantations in total. Data collected included litterfall at monthly intervals from October 2016 to April 2017, as well as decomposition conditions for assessment at the end of the experimental trials. Soil samples examined the species and number of macrofaunal and decomposition measurements of mesofauna by using Lamina bait scale to analyze nutrient content. Results showed the litterfall of leaves, twinges, and fruits in rubber monoculture and rubber-based agroforestry plantations were not significant between pair comparisons. This showed leaves fell at a high incidence. However, RT experienced a higher trend in litterfall. Decomposing litterfall was also not significant between pair comparisons, but when compared by associated plant species found that RT trends were more likely to experience higher decomposition rates and the litter index was higher as well. Macrofauna in the topsoil (0-5 cm) and subsoil (5-10 cm) were not significant. The composition of mesofauna was found at high decomposition rates in RF, RP, and RT. Organic matter and nutrient contents were not significant in both soil layers. Our data emphasizes that rubber-based agroforestry plantations help regulate C and nutrient cycles, implying that external input fertilizer management requirements for rubber farmers decreased.

Food waste is a vast issue global, including in Malaysia. Food waste brings negative impacts, including increasing food production costs, impact on human health, and environmental degradation. Malaysian’s animal- and plant-based diet preferences affected the desired food waste decomposition method as most of the methods only allow plant-based material to be utilized as food waste compost. The objectives of this study were to understand Malaysians' awareness of food waste behaviour and the food waste component for the decomposition. Malaysians usually produce more plant-based food waste than animal-based food waste. Most Malaysians have a high awareness of causes and impact of food waste, but they lack action on food waste reduction. Bio-compost is believed to be the most effective method to manage food waste, and most of them were willing to have it at home. However, some of them are unwilling to have a compost pile at home because there is no time to take care of it.

Oxisols are dominated by variable charge minerals in their clay fraction, containing an insufficient amount of Ca and Mg in their soil solutions. Under natural conditions, cocoa grown on the soils is subjected to the stress of low pH and Al and/or Mn toxicity, which eventually produces low yields. This chapter discusses the chemical properties of Oxisols in Malaysia and explains how the productivity of the soils is enhanced using lime or basalt, which increases soil pH. When the pH goes up above 5, Al in the soil solutions is precipitated as inert Al-hydroxides, with the concomitant elimination of toxic Mn. The increase in pH would result in the increase of the CEC, attributed to the reaction of the variable charge minerals present in the soils. Basalt application would also lower pH of the soils, which further increases the CEC. On dissolution, lime supplies Ca and Mg into the soils, and basalt not only releases these metals, but also K, P, and S. Ca, by itself, is able to reduce Al toxicity. One of the best methods of alleviating the infertility of Oxisols for cocoa cultivation is to apply basalt in combination with organic materials. Growing cocoa on Oxisols requires heavy application of NPK fertilizers, usually in the form of ammonium sulfate, rock phosphate, and muriate of potash, respectively. Occasionally, kieserite is applied to increase Mg reserve in the soils. Application of a high amount of N fertilizer will in the end acidify the soils, but it will be offset by the production of hydroxyl ions due to the specific adsorption of phosphate and sulfate ions on the surfaces of the oxides of Fe present in the soils. In that way, the production of cocoa on the Oxisols of Malaysia is sustained.