Soil improvement potential of weeds biomass applied as green manure in marginal land

Abstract

Abstract. Hamdani AD, Sulistiyowati E, Khusnuryani A. 2017. Soil improvement potential of weeds biomass applied as green manure in marginal land. Trop Drylands 1: 12-16. Weeds have been long considered to have negative effect on crops due to competition. Yet, the presence of weeds can be used to build up organic matter and chemical contents of degraded soil. This study aimed to assess the potential of three weed species, i.e. Chromolaena odorata, Mikania micrantha, and Synedrella nodiflora, to be applied as green manure to improve soil quality in marginal land, and to assess the best form of their practical application. Two forms of weed biomass application, fresh and dried chopped, were examined in a pot experiment containing soil from degraded land in Patuk, Gunung Kidul, Yogyakarta, Indonesia, and spinach (Amaranthus tricolor L.) as the test crop. The pots were laid out in a randomized complete block design with six replications. Laboratory analysis showed that manurial properties between the weeds were statistically similar, with the average of organic C, N, P and K at 36.9, 3.3, 0.1 and 1.6%, respectively. Of the chemical contents considered, the content of all chemicals measured in experimental soil had increased, particularly the available K₂O from 3.33 to the average of 46.33 ppm. The spinach growth and yield resulting from the treated soils were superior to that from untreated soils. However, there were no significant differences in the plant’s response between the types of weeds. Rather, better growth and yield of spinach have resulted from soil treated with dried chopped weed biomass. Thus, weed biomass can be used to improve soil organic matter and therefore should be incorporated with soil fertility maintenance.