IMPROVEMENT OF SOIL QUALITY THROUGH MICROAGGREGATES FORMATION BY EARTHWORM

• Main Author: Supriadi, Aep
• Format: Dissertations
• Language: Indonesia
• Subjects: Ilmu hayati ; Biologi
• Online Access: https://digilib.itb.ac.id/gdl/view/36815
• Institution: Institut Teknologi Bandung

Soil degradation is a 21st century global problem that is especially severe in the tropics and sub-tropics. The impact of degraded soil has affected the habitat of soil fauna destruction and loss of soil biological ability, loss of soil resistance and resilient. Some facts indicate of soil degradation decreased soil ecosystem services, and agricultural production. The objectives of research is to improve quality of degraded soil through microaggregates formation by earthworms. The research was conducted at Gunung Geulis area, Sumedang Regency, West Java – Indonesia and in the laboratory of School of Life Sciences and Technology, Institut Teknologi Bandung, Indonesia. Research carried out in two phases, i.e the identification soil quality, to determine the quality of degraded soil based on microaggregates, and the improvement of soil quality by added soil organic matter and indegenous of earthworms. Survey methode and sampling was done at 5 different land use types: 1) Agroforestry (= AF) dominated by pine trees; 2) Agrosystem–banana (= AS1) 3) Agrosystem–cereals (= AS2); 4) Agrosystem– banana–cereal (= AS3); 5) Protected forest (= FS). Soil sampling was conducted by sistematic method, the result of identification study area. The result of soil quality assessment shows that soil belongs to inceptisol type with Udepts sub-ordo and Eutrudepts group, and belongs to kaolinit mineral. The soil quality in five dif-ferent land use types shows poor soil quality at FS (0.4814), AF (0.3985), and very poor soil quality at AS1 (0.3881), AS2 (0.3614) and, AS3 (0.3981), on a max-imum scale 0.9565. The soil in the study area has a high proportion of mi-croaggregates but resistance to water dispersion (Water Aggregate Stability) en-tered at intervals of moderate (69.31%), the stable aggregate is very poor (28.13%) with a poor aggregate stability index (44.05). The order among of five soil fauna found, there were soil engineers is Haplotaxida and Hymenoptera, i.e earthworms (Amynthas aeruginosus, Amynthas illotus species-group), ant (Solenopsis, Formicidae (Anoplolepis gracilipes, Diacamma sp., Lasiolepis sp., Nylanderia sp., Pheidole sp. 1, Pheidole sp. 2, Cardioconyla sp 1, Tetramorium sp., Myrmicaria sp., Pheidologeton, Camponotus sp., Polyrhachis sp 1). The destructive experimental design in the laboratory was used for the.second research methode, i.e Randomized Block Design with factorial pattern. The expereiments using degraded soil was collected from Agrosystem-cereal (AS2). The quality of degraded soil (AS2) was determine has very low quality index in the previous study. The experiment consisting of three factors, namely the aggre-gate grain size (A), earthworms (B) and the dose of compost (C). Aggregate (A) Factors comprises four levels: macroaggregates (a0 = 2.000 – 0.841) ?m , iv messo-aggregate (a1 = 0.841 – 0.250) ?m, microaggregates (a2 = 0.250 – 0.044) ?m, and aggregate mixture (a3) with a ratio of 27% macroaggregates, 54% messo-aggregate and 19% of microaggregates, almost like a land area of re-search. Earthworms of Megascolecidae ( B) factors consists of two levels ie with-out earthworms (b0), with earthworms (b1) and compost (C) consists of two levels ie without compost (c0) and with compost (c1). So there are 16 combinations of treatments Each combination treatment was repeated twice. so that all amounted to 96 pots. The compost was added to increase soil organic carbon (SOC) at least 20% In each treatment, 17 individuals (about 20 g) of earthworm (Amynthas illotus - Megascolecidae) were used for the treatments. These experiments con-ducted in random block design with factorial pattern and repeated twice. A total of 96 pots were prepared and 32 pots were examine every month. The mechanism of soil quality improvement in one month is most influenced by the increase in po-tassium (6 - 7 times) and the fast drainage pore. The fast drainage pore provide access of water and air distribution to improve the process of decomposition and humunification organic matter and soil pH. The mechanism of soil aggregate stability improvement in two and three month is most influenced by the increase of dissolved organic carbon (4 times), while on soil quality is most influenced by calcium.exchanged. Improvements in physical properties occur in bulk density, pore distribution, stable aggregate, microaggregate and macroaggregate en-hancement, surface area and micro pore volume. The soil is more axle with in-creased macro pore (> 8.6 ?m) although the slow drainage pore is declining, while at fieldy capacity pore there was an increase in available water pore (0.2 - 8.6 ?m) and was declining on pore of water not available (<0.2 ?m). Improvement of soil physics-chemical properties of an increase in humic substance, stable or-ganic karbon that are more affected by earthworms while exopolisakarida by compost. Improvements in soil quality are indicated by changes in chemical prop-erties ie cation exchange capacity rising from low or moderate to high (25 – 40 cmol(+).kg-1), saturation of bases from medium to very high above 70%., and carbon stable in microagregates. The highest number of stable carbon that can be sequestered in micro aggregate by the interaction of earthworms and compost as 25.00 tonnes.ha-1, while the interaction of earthworms and aggregates occurred in the meso aggregate of 25.96 tonnes.ha-1. Aggregate stabilization occurs after one month, indicated by aggregate surface changes, more roughage, more pores, and a change in the proportion of microaggregates. The highest number of micro pore volume in micro aggregate as the results of interaction each month one, two and three months was 0,58 cc.g-1 on messo aggregate, on macro aggregate 1,33 cc.g-1 and 2,20 1,33 cc.g-1 respectively, while on surface area in micro aggregate in mixed agggregate was 312,77 m2g-1, 591,23 m2g-1, dan 445,80 m2g-1 respectively. The process of microaggregate and macroaggregate formation oc-curs simultaneously in one and two months with the coefisien of proportion 0,718%, dan 0,827%. Respectively.