Perbaikan lahan bekas tambang pasir besi dengan aplikasi bahan humat dan kapur untuk tanaman semangka (Citrullus vulgaris scard)

Abstract

Activities in iron sand mining affects the degradation of physical and chemical properties of soils. Several soil problems of ex-mined land of iron sand mining are low nutrient availability, low available soil water, high soil temperature, porous structure and uneven topography. Improvement of the such soil needs application of appropriate soil ameliorants such as humic substance and lime. It has been known that humic substance can be obtained by extracting organic matter, therefore, application of that material may improve the chemical, physical, dan biological properties of soil. The purpose of this research is to examine the effect of humic substance and lime application on ex-mined land of iron sand mining on soil characteristics, growth, and production of watermelon. The research was conducted in ex-mined land of iron sand quarry of PT. Antam (Aneka Tambang) at Patutrejo, Grabag village, Purworejo, Central Java from March 2010 until March 2011. The field research used Split Plot of Complitely Randomized Design consisted of two factors: Humic substance (H0: 0; H1: 7.5; H2:15; and H3: 22.5 L/Ha) and Lime (K: 0 and K1:100 kg/Ha) with three replications. The parameters of growth and production (shoots length, leaf number, segment number, male flowers number and fruit weight) were measured to determine the effect of the treatments. The chemical properties of soils were analyzed for monitoring the soil properties changes. The results showed that humic substance and lime application increased the availability of P, K, Ca, and Mg. Humic substance has carboxil and fenolic clusters those have capability to bound Al and Fe ions from soil solution for forming low solubility of complex compounds. Therefore, the concentration of free Al and Fe ions in the solution will decrease causing the available of phosphate increase. Humic substance increased the shoot length, leaf number, male flowers number, and the segment number. The application of humic substance as much as 22.5 L/Ha increase the watermelon production by 28% from 6.15 ton/Ha at K0H0 to 7.88 ton/Ha at K0H3 treatment. Leaf spot disease, soft rot, and pest snails affected growth and yield of watermelon.