Effect of azolla green manure on wetland rice and available of azolla-N

A pot experiment and a field experiment were conducted to investigate the effect of Azolla pinnata, applied alone or in combination with urea, on rice plants under Malaysian conditions. Results of the pot experiment show that application of azolla significantly increased the number of tillers and panicles, dry straw weight and grain yield over the control; similar results were obtained from the application of urea. There was no significant difference between the various azolla treatments. In the field, the recovery rate with azolla application at 30 DAT was higher than when applied at transplanting; results with urea-N application were similar

METHANE EMISSION FROM PADDY FIELDS AS INFLUENCED BY DIFFERENT WATER REGIMES IN CENTRAL JAVA

The concentration of methane (CH4) in the atmosphere is increasing at 1% per annum and rice fields are one of the sources that contribute to about 10-15% of the atmospheric CH4. One of the options to reduce greenhouse gas emission from rice fields is probably through water management. A field study was conducted to investigate the effects of water management practices on CH4 emission from rice field plots on a silty sand Aeric Tropaquept soil at Research Station for Agricultural Environment Preservation, Jakenan, Central Java, Indonesia, during the dry season of March to June 2002. Four water regimes tested were: (1) 5 cm continuous flooding (CF), (2) 0-1 cm continuous flooding (ST), (3) intermittent irrigation (IR) where plots received continuously 5 cm of flooding with two times of draining at 15-20 and 25-30 days after transplanting (DAT), and (4) pulse irrigation (PI) where plots were watered until 5 cm level and left to dry by itself until the water table reached 30 cm beneath soil surface then watered again. The total CH4 emissions of the four water treatments were 254, 185, 136 and 96 kg CH4 ha-1 for CF, ST, IR and PI, respectively. Methane emission increased during the early growing season, which coincided with the low redox potential of -100 to -150 mV in all treatments. Dry matter weight of straw and filled grain among the water treatments did not show significant differences. Likewise, total grain yield at 14% moisture content was not significantly different among treatments. However, this result should be carefully interpreted because the rice plants in all water treatments were infested by stem borer, which reduced the total grain yield of IR64 between 11% and 16%. This study suggests that intermittent and pulse irrigation practices will be important not only for water use efficiency, but also for CH4 emission reduction

Methane Emission From Paddy Fields as Influenced by Different Water Regimes in Central Java

The concentration of methane (CH4) in the atmosphere is increasing at 1% per annum and rice fields are one of the sources that contribute to about 10-15% of the atmospheric CH4. One of the options to reduce greenhouse gas emission from rice fields is probably through water management. A field study was conducted to investigate the effects of water management practices on CH4 emission from rice field plots on a silty sand Aeric Tropaquept soil at Research Station for Agricultural Environment Preservation, Jakenan, Central Java, Indonesia, during the dry season of March to June 2002. Four water regimes tested were: (1) 5 cm continuous flooding (CF), (2) 0-1 cm continuous flooding (ST), (3) intermittent irrigation (IR) where plots received continuously 5 cm of flooding with two times of draining at 15-20 and 25-30 days after transplanting (DAT), and (4) pulse irrigation (PI) where plots were watered until 5 cm level and left to dry by itself until the water table reached 30 cm beneath soil surface then watered again. The total CH4 emissions of the four water treatments were 254, 185, 136 and 96 kg CH4 ha-1 for CF, ST, IR and PI, respectively. Methane emission increased during the early growing season, which coincided with the low redox potential of -100 to -150 mV in all treatments. Dry matter weight of straw and filled grain among the water treatments did not show significant differences. Likewise, total grain yield at 14% moisture content was not significantly different among treatments. However, this result should be carefully interpreted because the rice plants in all water treatments were infested by stem borer, which reduced the total grain yield of IR64 between 11% and 16%. This study suggests that intermittent and pulse irrigation practices will be important not only for water use efficiency, but also for CH4 emission reduction

Waste to health: organic waste management for sustainable soil management & crop production

Organic waste management is essential not only in turning waste into wealth but more importantly in improving environmental quality and health, and contributing to sustainable crop production when it is recycled in the agricultural sector. The agricultural sector in Malaysia produces a tremendous amount of waste which has traditionally been burnt or simply dumped (a common practice till now) making it a source of greenhouse gas emissions and other environmental problems which affect human health. More recently, due to the prohibition of open burning of organic wastes, it has become a trend to convert wastes into wealth, i.e. value added products. Research has escalated to investigate various technologies with the aim of reducing waste through good waste management practices, i.e. recycling in agriculture or conversion into useful products for commercialization. However, returning organic wastes back to agricultural land simply by mulching(e.g. oil palm empty fruit bunches (EFB) applied fresh from the mill or as processed EFB mats to newly transplanted palms and mature palms) or incorporation of crop residues into soils after harvesting contributes to recycling of nutrients and organic matter back into soils, thus building up soil quality and health, prevents land degradation and increases soil productivity. Composting of organic wastes (not limited to agricultural wastes) reduces the bulk of the wastes and concentrates nutrient contents. This process not only converts the wastes into value-added products such as organic fertilizers, soil amendments and soilless potting media but also avoids wastes being exposed to the environment and vulnerable to greenhouse gas emissions (nitrous oxide and methane) and pollution of natural resources (leaching into groundwater and surface run-off into surface waters). The use of soilless potting media derived from organic wastes could partially or totally replace the use of peat which is a slowly renewable resource.Apart from this, there has been an increase in interest, in the last decade, in transforming organic wastes into biological charcoal or biochar under controlled conditions, such as pyrolysis and gasification, with the main objective of using it as a soil amendment in agricultural land, particularly for naturally infertile or degraded soils. Biochar contains carbon that is potentially resistant to microbial degradation and has dual functions. Firstly, biochar improves soil quality and crop productivity due to its high porosity and sorption properties. Secondly, biochar increases carbon storage or sequestration in soil thus reducing carbon dioxide in the atmosphere and mitigating global warming and climate change. Sustainable management and recycling of organic wastes in agriculture is a holistic approach which should be pursued not only with the sole objective of converting wastes into wealth but more seriously for its various benefits to crop production, the environment (clean water and air, and balanced carbon cycle) and, ultimately, human health

Durability of Rubbercrete Containing Fly Ash and Nano Silica in terms of Deterioration Mechanism through Chemical Attack

Several researches have been conducted to determine the properties of rubbercrete, a concrete containing crumb rubber as partial replacement to fine aggregate. The benefits of rubbercrete includes lighter in weight, more ductile, better workability, and better sound absorption. However, crumb rubber hydrophobic properties cause rubbercrete to have a lower compressive strength and durability compare to normal concrete. Therefore, Nano silica and fly ash is added into the mixture to counter this problem. This thesis presents the study of rubbercrete durability in terms of its deterioration mechanism through chemical attack. The thesis details on the effect of acid attack, sulfate attack and efflorescence to the mixture. For this work, the strength of rubbercrete is improvised by addition of Nano Silica into the mixture. Thirty trial mixes were prepared to produce concrete cubes of dimension 100 mm x 100 mm x 100 mm. The composition of rubbercrete focus on 0%, 15%, and 30% crumb rubber (CR) as replacement of fine aggregate, 0%, 2.5% and 5% addition of Nano Silica to increase its compressive strength, 0%, 35% and 70% of fly ash to replace cement and 0.25%, 0.3% and 0.35% of water-cement ratio

THE EFFECT OF RICE CULTIVARS ON METHANE EMISSION FROM IRRIGATED RICE FIELD

Rice plants have been reported to affect methane (CH4) emission from rice fields. The objectives of this study were to determine the effect of rice cultivars on CH4 emission from flooded rice and to develop crop management strategies with low emitting rice cultivars while sustaining high yield. The four rice cultivars studied were Memberamo, Cisadane, IR64, and Way Apoburu. The CH4 emissions were determined in the wet season of 2001/2002 (November-February) using an automated closed chamber technique in an irrigated field condition. Farmyard manure at the rate of 5 t ha-1 was given to the plots to ensure carbon was not limited. Root weight, root length, biomass, and number of tillers were determined at 17, 36, and 57 days after transplanting (DAT). The results showed that the mean CH4 emission was highest in the plot planted with Cisadane (94.8 kg CH4 ha-1), and the lowest with IR64 (37.7 kg CH4 ha-1). The plots treated with emberamo and Way Apoburu resulted an intermediate CH4 emission at the average of 61.1 and 58.9 kg CH4 ha-1, respectively. There was no significant difference in yield between the cultivars tested. The yield of Memberamo, Cisadane, IR64, and Way Apoburu were 5.882, 5.764, 5.873 and 6.065 t ha-1, respectively. Statistical analysis showed that there were no significant differences in the root weight and root length among cultivars. However, Cisadane gave the highest dry matter weight (222 g hill-1) at 57 DAT compared to the other cultivars (175-190 g hill-1). Plant tillers did not show significant differences between the cultivars. Regression analysis showed that CH4 flux was significantly related with root weight, root length, aboveground biomass, and number of plant tillers. This finding shows that the use of selected cultivars, such as IR64, can potentially lower CH4 emission without scarifying yield

3,3′-Di-n-propyl-1,1′-[p-phenyl­enebis(methyl­ene)]diimidazolium dibromide

The asymmetric unit of the title compound, C20H28N4 2+·2Br−, consists of half a 3,3′-di-n-propyl-1,1′-[p-phenyl­enenis(methyl­ene)]diimidazolium cation and a bromide anion. The cation is located on an inversion center and adopts an ⋯AAA⋯ trans conformation. In the crystal, the cation is linked to the anions via weak C—H⋯Br hydrogen bonds

Nitrogen Management in a Maize-Groundnut Crop Rotation of Humid Tropics: Effect on N2O Emission

Development of appropriate land management techniques to attain sustainability and increase the N use efficiency of crops in the tropics has been gaining momentum. The nitrous oxides (N2Os) affect global climate change and its contribution from N and C management systems is of great significance. Thus, N transformations and N2O emission during maize-groundnut crop rotation managed with various N sources were studied. Accumulation of nitrate (NO3 –) and its disappearance happened immediately after addition of various N sources, showing liming effect. The mineral N retained for 2–4 weeks depending on the type and amount of N application. The chicken manure showed rapid nitrification in the first week after application during the fallow period, leading to a maximum N2O flux of 9889 μg N2O-N m–2 day– 1. The same plots showed a residual effect by emitting the highest N2O (4053 μg N2O-N m–2 day– 1) during maize cultivation supplied with a halfrate of N fertilizer. Application of N fertilizer only or in combination with crop residues exhibited either lowered fluxes or caused a sink during the groundnut and fallow periods due to small availability of substrates and/or low water-filled pore space (<40%). The annual N2O emission ranged from 1.41 to 3.94 kg N2O-N ha–1; the highest was estimated from the chicken manure plus crop residues and half-rate of inorganic N-amended plots. Results indicates a greater influence of chicken manure on the N transformations and thereby N2O emission