A. R. Anuar

Effects of Controlled Release Urea on the Yield and Nitrogen Nutrition of Flooded Rice

Nitrogen (N) loss is one of the key problems faced by rice farmers, and Nitrogen-use efficiency in rice is often poor as a result of high N loss through volatilization, leaching, and denitrification. One of the ways to improve N efficiency is by using controlled-release urea (CRU). The CRU generally outperformed granular urea fertilizer in reducing N losses, stimulating plant growth, and increasing N concentrations. A field experiment with the flooded rice variety MR220 was conducted to compare the effect of six different types of CRU fertilizers on yield and N nutrition of a flooded rice cultivar. Bakau series soil (Typic Tropaquept) was used in this study. Rice plants were grown in a cylindrical culvert measuring 90 cm in diameter by 60 cm in height, and all culverts were filled with soil (approx. 210 kg). The soil was flooded and preincubated for 3 weeks to stabilize physiochemical properties before sowing. The experiment was carried out over two planting seasons on the same plot using a completely randomized design (CRD) and was replicated three times. The CRUs evaluated were CDU Uber-10, Meister-20, Meister-27, humate-coated urea, Duration type V, and sulfur-coated urea (gold–N). Fertilizer was applied once throughout the study. For both seasons, CRU-treated plants had significantly greater rice yields [6 t ha−1 (first planting harvest) and 6.2 t ha−1 (second planting harvest)] than urea-treated plants [3.7 t ha−1 (first planting harvest) and 2.2 t ha−1 (second planting harvest)], respectively. The N accumulations in rice straw and rice grains of the CRU-treated plot were significantly greater than in the control. It can be inferred that CRU performs significantly better than granular urea. This finding is important, considering the usually high N losses in rice-growing areas.

A Modified Way of Producing Humic Acid from Composted Pineapple Leaves

ABSTRACT Purification of humic acid (HA) is time-consuming (takes between 2 to 7 days). A study was conducted to investigate whether HA produced from composted pineapple leaves could be purified within a day through washing with distilled water. Standard procedures were used to produce 0.1 M KOH and pineapple leaves compost. The KOH was used to extract HA in the compost using standard methods with some modifications. The HA was purified by suspending it in 100 ml distilled water, equilibrated for 1 hour, centrifuged for 15 minutes, supernatant decanted, filtered through glass wool and the liquor analyzed for K, Ca, Mg, Na, Zn, Mn, and Cu using an atomic absorption spectrophotometer (AAS). This procedure was repeated four times after which the washed HA was oven dried at 30°C to a constant weight. Washing HA for four consecutive times within a day was able to reduce the ash content of the HA to 0.1%, a value less than the generally accepted value of less than 1%. This observation was attributed to the remarkable decrease in K, Ca, Mg, Na, Zn, Mn, and Cu with washing. This finding can help in facilitating the production of K-rich humate (organically based fertilizer) from composted pineapple residues in a relatively short time since the HA can be purified within a day for its reconstitution to produce K-humate (38% K) instead of the conventional method that takes between 2 to 7 days.

Towards Sustainable Use of Potassium in Pineapple Waste

Due to the 1997/98 haze problem in South-East Asia and the increasing need for sustainable food production and development, the usual management of crop residues (including pineapple wastes) through burning is prohibited. As a result, the need for alternative uses of pineapple wastes in pineapple production has been emphasized. This study investigated an environmentally friendly means of recycling pineapple leaves for agricultural use. Pineapple leaves were shredded and composted in a composting drum for 30 days. Part of the shredded leaves was ashed in a muffle furnace for 4 h. Humic acid (HA), K-fulvate, and K in HA and compost were analyzed using standard procedures. An ash to water ratio of 1:7 was used to extract 0.1 molar (M) KOH from the shredded leaves. The 0.1 M KOH contained 50% K and was able to extract 20% HA from the composted pineapple leaves. Percent K in the fulvate using 0.1 M KOH was 43. Besides serving as a foliar spray (supplement soil application K fertilizers), source of K for freshwater fish (e.g., tilapia), the HA produced can be used as a soil conditioner. Studies show that between 0.05—0–01 g of HA per kg soil retards runoff by 36% in sandy and sandy loam soils. The K-fulvate can be used as a fluid fertilizer. In addition, the pH of 2 of the K-fulvate suggests it could be used to dissolve phosphate rocks, particularly those in the arid regions where high soil pH does not facilitate the dissolution of these important rocks that serve as one of the sources of phosphorus fertilizer in agriculture.

Effects of extraction and fractionation time on the yield of compost humic acids

Abstract The yield of humic acids (HA) partly depends on the period of isolation (extraction and fractionation), extractants used, and conditions such as temperature, pre‐treatments, and compost:extractant ratios of extraction. This study was conducted to investigate whether a relationship could be separately established between extraction time, fractionation time, and the yield of HA from composted pineapple (Ananas comosus) leaves, as well as the relationship between both variables (extraction time and fractionation time) on the yield of HA from this compost. Standard procedures (with some modifications) using 0.1M NaOH were used to isolate HA from compost. Although there was a quadratic relationship between extraction time and HA yield, there was no relationship between fractionation time and HA yield. This observation enables the isolation of HA of compost within 24 h or less instead of the existing average time of 48 h, hence helping in facilitating the idea of producing potassium humate as a foliar potassium fertiliser from composted pineapple leaves and related crop residues instead of open burning, a practice that has undesirable environmental effects.

Effect of Residue Management Practices on Yield and Economic Viability of Malaysian Pineapple Production

ABSTRACT This paper communicates the effect of in situ burning of pineapple residues (IBPR), in situ decomposition of pineapple residues untouched (IDPR), and the application of the zero burn technique (ZBT, i.e., slashing, raking and stacking of leaves, crowns, and peduncles from 2 m (wide) beds into 3 m (wide) beds, respectively, on yield. It also compares the economic viability of these residue management practices. The Net Present Value (NPV) was used to compare the economic viability of the three residue management practices. The three residue management practices did not significantly improve yield. Taking into account the Cost environmental Pollution associated with burning of pineapple residues, the NPV analysis revealed that either the IDPR or the ZBT practices can serve as an economically competitive alternative to the usual method of burning pineapple residues.

Production of Humic Acid from Pineapple Leaf Residue

ABSTRACT The study was carried out with the following objectives: (i) to quantify the amount of humic acid (HA) that could be extracted from composted pineapple leaf residue using potassium hydroxide (KOH) produced from pineapple leaf residue, and (ii) to compare the elemental composition, functional groups, and spectral characteristics of HA extracted from composted pineapple leaf using 0.1 M KOH from pineapple leaf and that of analytical grade (0.1 M KOH). The 0.1 M KOH from pineapple leaf residue extracted 20% HA from composted pineapple leaf residue while that of the analytical grade (0.1 M KOH) extracted 30%. The elemental composition (C, H, N, O, and S), functional groups (carboxylic, phenolic OH, and total acidity), and spectral characteristics of the HA extracted using the 2 extractants were generally similar. Potassium hydroxide from pineapple leaves can be used to extract some reasonable amount of HA without appreciably altering the elemental and functional groups constitution as well as the spectral characteristics. The potential of using KOH from pineapple leaf residue in HA studies appears promising.

Economic Viability of Pineapple Residues Recycling

ABSTRACT A study was conducted to investigate whether pineapple residues removal before replanting (RM2) could serve as an economically competitive alternative to the existing in situ burning of pineapple residues before replanting (RM1). The Net Present Value (NPV) was used to compare the economic viability of the two residue management practices. Taking into account the cost of environmental pollution associated with burning of pineapple residues, the NPV analysis revealed that RM2 can serve as an economically competitive alternative to RM1.

Apparent Electrical Conductivity in Correspondence to Soil Chemical Properties and Plant Nutrients in Soil

Spatial variability and relationship between soil apparent electrical conductivity (ECa), soil chemical properties, and plant nutrients in soil have not been well documented in Malaysian paddy fields. For this reason precision farming has been used for assessing field conditions. ECa technique for describing soil spatial variability is used for soil data acquisition. Soil sampling provides the data used to make maps of the spatial patterns in soil properties. Maps are then used to make recommendations on the variation of application rates. The main purpose of the authors in this study was to generate variability map of soil ECa within a Malaysian rice cultivation area using VerisEC sensor. The ECa values were compared to some soil properties after delineation. Measured parameters were mapped using kriging technique and their correlation with soil ECa was determined. Through this study the authors showed that the EC sensor can determine soil spatial variability, where it can acquire the soil information quickly.

Phosphorus Fertilizer use in Pineapple Cultivation with in situ Residues Burning on Organic Soils

Abstract In Malaysia, pineapples are grown on peat soils, but most phosphorus (P) fertilizer recommendations are made without due quantification of P uptake; the distribution of P in roots, stem, leaves, peduncle, fruit, and crown; or loss through leaching even though P retention in peat soils is low. This study was conducted to determine applied P‐use efficiency under a conventionally recommended fertilization regime in pineapple cultivation with in situ residues burning before replanting. Results showed that most of the P uptake in pineapple can be found in the fruit, stem, leaves, and crown, but the general trend of P distribution was in the order of fruits>leaves>stem>crown>peduncle>roots. Phosphorus recovery in pineapple cultivation was about 40%, and this low recovery was attributed to leaching. Hence, fertilizer recommendations need to take into consideration P loss through leaching. This will help to increase P‐use efficiency because it is not possible to build up P content of peat soils. As a result, the need to assess the possibility of side‐dress applications of phosphatic fertilizers on peat soil is necessary.

Comparison of soil phosphorus tests for assessing plant availability of phosphorus in an ultisol amended with water-soluble and phosphate rock sources.

The effectiveness of different soil tests in assessing soil phosphorus (P) in soils amended with phosphate rocks (PRs) is uncertain. We evaluated the effects of triple superphosphate (TSP) and PRs on extractable P by conventional soil tests (Mehlich 3 [Meh3] and Bray-1 [B1]) and a nonconventional test (iron oxide–impregnated paper, strip). Extracted amounts of P were in the order: Meh3 >B1 > strip. All the tests were significantly correlated (p = 0.001). Acidic reagents extracted more P from TSP than PRs, while the strip removed equal amounts from the two sources. The P removed by the three tests was related significantly to dry matter yield (DMY), but only in the first harvest, except for B1. Established critical P levels (CPLs) differed for TSP and PRs. In PR-fertilized soils, CPLs were 27, 17, and 12 mg P kg-1soil for Meh3, B1, and strip, respectively, and 42, 31, and 12 mg P kg-1 soil, respectively, in TSP-fertilized soils. Thus, the strip resulted in a common CPL for TSP and PRs (12 mg P kg-1 soil). This method can be used effectively in soils where integrated nutrient sources have been used, but there is need to establish CPLs for different crops. For cost-effective fertilizer P recommendations based on conventional soil tests, there is a need to conduct separate calibrations for TSP- and PR-fertilized soils.