Ameliorative potential of rice hull and straw in the ecological restoration of mine degraded soils | IJAAR 2022

Author Information

Gelian Aranas-Rasonable  from the Institute of the Cabadbaran City National High School, Brgy. 12, Cabadbaran City, Agusan del Norte, Philippines.

Grethyl Catipay-Jamero from the Institute of the Cabadbaran City National High School, Brgy. 12, Cabadbaran City, Agusan del Norte, Philippines.

Chris P. Rasonable from the Institute of the Calamba National High School, Brgy. Calamba, Cabadbaran City, Agusan del Norte, Philippines.

Gemma A. Asufre from the Institute of the Department of Agriculture, Region XIII, Butuan City, Agusan del Norte, Philippines.

Journal Name

 International Journal of Agronomy and Agricultural Research | IJAAR

Abstract

Rice hull and straw are renewable wastes contain 28-30% of inorganic and 70-72% of organic compounds. Its ameliorative potential in enhancing the physicochemical properties of mine degraded soils was investigated. Soils collected from Backfill Material/Overburden (BM) and desilted materials (DM) from settling ponds of Carrascal Nickel Corporation (CNC) were used following six treatments. BM and DM from settling ponds were treated with rice hull and rice straw with 2:1 ratio by weight, respectively. After ameliorating soils from overburden and silted materials from CNC with rice straw and rice hull, observations showed that there are no significant differences in pH, % Organic Matter (OM) and phosphorous (P) between treatments; there is high significant difference (p<0.01) in potassium (K) between treatments except between treatment 3 (soil 1 with rice straw) and treatment 6 (soil 2 with rice hull) where there is no significant difference noted; and the concentrations of Ca, Mg, S and Zn in soils with rice hull did not differ with soils before amelioration, but differed to soils with rice straw, while results in soil texture exhibited otherwise. Therefore, rice straw and rice hull have ameliorative properties that will improve the physico-chemical characteristics of mine degraded soils. It is recommended that rice straw and rice hull will be allowed to decompose in mine degraded soils to enhance its physico-chemical properties. It is also recommended to conduct studies on the response of different crops to mine degrade soils ameliorated with rice straw and rice hull. 

Introduction

Nickel mining operations are large industries in the Philippines that extensively impacted large land areas. The surface mining of nickel seriously damages the surface soil, removing the local flora and fauna with the removal of the soil surface horizons. Also, degradation problems are sometimes caused by mining waste such as overburden, discards and mine effluents. Revegetating the area is one way to stabilize the surface soil. However, mine degraded soil is a difficult medium to prepare for a successful revegetation. It is possible to revegetate the covering topsoil, but the sustainability of conventional procedures is often poor. Liming and fertilizing the covering topsoil, does not necessarily ensure a viable growth medium for plants for prolonged periods. Vegetation would hardly survive due to unsustainable growth of the roots. As a result, the covering topsoil becomes unstable, and susceptible to erosion. Fertilization and liming to augment soil nutrient and regulate soil pH are recommended but very expensive. Large amounts of lime and fertilizer are also used to rehabilitate these areas, but are often not sustainable as the soil is bare and susceptible to erosion during rainfall and high temperature during dry months which considerably changes soil pH. However, discontinuation of fertilization can cause decrease production and vegetative cover on marginal sites. Presently, no effective and economical mitigation is being recommended to revegetate the area and create a sustainable system. The challenge is thus to find alternative methods to which will be sustainable.

Understanding that surface mining often require removal of surface soil horizons instantly shrinks the soil organic matter pool. This resulted to the ability of soil to replenish organic matter via net primary production that is repressed by altered nutrient, water and soil temperature regimes. Then, waterholding capacity is reduced by lack of soil organic matter and by increased runoff capacity due to lower porosity (increased bulk density) and infiltration. Soil microbial activity is also negatively affected. Amelioration using organic amendments affect soil properties in numerous and variable ways (Larney et al., 2009). Soil organic matter is generally considered the single most important property affecting quality and functioning of soils (Gregorich et al., 1994). As expected, application of organic amendments results in an immediate increase in soil organic carbon, which is generally proportional to the amount of carbon applied (Chantigny et al., 1999). However, in cases of high background levels and or high variability, changes in soil organic carbon following low or moderate application rates may not be measurable or detectable (Viaud et al., 2011). 

The rate of decomposition of organic amendments and soil organic carbon remaining over the long term vary with intrinsic quality of the amendment (Lashermes et al., 2009). Carbon in organic amendments was originally fixed by plants through photosynthesis. The chemical composition and physical characteristics of organic amendments will depend on the type of vegetation from which they are derived (e.g., trees vs. annual agricultural crops) and on the fate and transformation of the plant carbon following its harvest. For instance, cereal straw can either be incorporated directly into the soil or become part of manure (via bedding), which is eventually land applied in fresh or composted forms. If the latter, it will undergo decomposition (mineralization and transformation) that will modify its properties, more so during composting, where labile carbon forms are mineralized such that the remaining carbon is more stable and results in greater increases in soil organic matter per unit of carbon applied than fresh plant materials in the long term (Lashermes et al., 2009). Effects of the organic matter to the soil can be direct, through the intrinsic properties of the organic amendments themselves, or indirect, by modifying soil physical, biological and chemical properties. Hence, the type of organic amendments used as ameliorant matters. High organic carbon content provides an instant energy source, which boosts soil microbial activity, and organic matter improves poor soil physical conditions resulting from topsoil loss and compaction.

While rice husk and straw are largely considered waste products are often burned in preparation for the next planting season or dumped on landfills (Gummert, 2003). Rice hull and rice straw are produced in volume during rice harvest in the Philippines. Burning of rice straws and other agricultural wastes contributes more to air pollution than vehicle emissions (Philstar Global, 2006). Hence, disposal of rice straw as a byproduct resulting from the cultivation of rice is causing worldwide environmental and health problems. According to rice farmers in Caraga region, rice hull and straw are burned as being the cheapest method of disposal. The practice which is observed to be common in rice fields in the region does not only generate smoke, but also breathable particulate matter and dust that contains crystalline silica and other health hazard substances (Damatty and Hussain, 2009). Approximately 5,073,880 tons of rice hull and straw are burned annually according to the Industrial Technology Development Institute (ITDI) of DOST, in every 250 kg of rice straw and 100 kg of rice hull burned per ton of rice produced.

Utilization of rice straw and rice husks has been practiced in the field for some time (Ponamperuma, 1982). Research has shown that assimilation of rice straw and rice hull with the soil can significantly improve soil properties through decreasing soil bulk density, improving soil pH, accumulating organic carbon, enhancing available nutrients and eliminating heavy metals from the system, which ultimately enhancing crop yields (Saunders and Williams, 1955). Rice hull and straw as annually renewable wastes contain 28-30% of inorganic and 70-72% of organic compounds (Sergienko et al., 2004). According to Koz’mina, (1976) the composition of the organic compounds includes C, H, O, N. The inorganic components are represented mainly by silica (Sergienko et al., 2004). These organic materials are not yet tested as ameliorant to mining degraded soil. Thus this study investigated the ameliorative potential of rice hull and straw in the ecological restoration of mine degraded soils. Specifically, the study determined the physicochemical parameters of mining degraded soils before and after the application of rice straw and rice hull; and the significant difference in the physico-chemical parameters of mining degraded soils before and after the application of rice straw and rice hull. The results of the study can be used as bases in recommending rice straw and rice hull in improving and restoring mine degraded soils. Utilization of rice straw and rice hull will also decrease volume of farm wastes and will improve soil properties by decreasing soil bulk density, enhancing soil pH, adding organic carbon, increasing available nutrients and removing heavy metals from the system, ultimately increasing crop yields. The study was conducted in three months’ period including the collection and analysis of sample. Experimental phase of the study was done in pot trials in controlled condition for thirty days. Analyses of soil samples was done in Integrated Laboratory of the Department of Agriculture Caraga Region. Check out more Ameliorative potential of rice hull and straw in the ecological restoration of mine degraded soils

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