ANNUAL CLOVER SPECIES AS WEED SUPPLYERS

The article discusses the results of using a new technique for suppressing weeds, including sowing annual legumes with high allelopathic properties and plowing them for green manure.

Yield, Decomposition, Mineralization and Nitrification of Annual Legumes in an Oxisol

Knowledge about seasonal and litter bag soil position effects on litter decomposition (k value), mineralization and nitrification rate of annual legumes in Puerto Rico is limited. This study determined dry matter yield (DMY), k value of litter bags placed below and above the soil surface, mineralization and nitrification rates of Lablab purpureus cv. “Rongai” and Mucuna pruriens (Velvet bean) seeded in the wet and dry season in Oxisol soils (Typic Eustrustox). There was an interaction (p < 0.05) for season and legumes on DMY, k value and N content. “Rongai” DMY was higher for the dry than wet season while Velvet bean had an opposite seasonal response. Higher k value occurred in the wet season for legumes, but “Rongai” had higher k than Velvet bean. For both legumes, N content was higher on litter bag placed below-ground in both seasons. However, in the wet season, there was less N in the above ground litter position. Higher inorganic N was observed at 90 days of soil incubation (DOI) suggesting that N was not available prior to 42 DOI. Nitrification rate was higher for “Rongai” at 22 DOI and lower at 42 and 90 DOI for both legumes. Both legumes enhanced inorganic N, but, regardless of season, Rongai supplied nutrients to the soil faster than Velvet bean. “Rongai” because of its higher k value than Velvet bean is recommended for fast growing row or vegetable crops in Puerto Rico.

Introduction of Dwarf Elephant Grass (Pennisetum purpureum cv. Mott) and Annual Legumes in the Disused Limestone Mining in Karst Gombong Area, Central Java, Indonesia

The aim of this research was to revegetate the disused limestone quarry by introducing dwarf elephant grass (Pennisetum purpureum cv. Mott) and annual legumes such as peanuts (Arachis hypogaea L.), soybeans (Glycine max), cowpeas (Vigna unguiculata) and mung beans (Vigna radiata). The study was conducted experimentally in a disused limestone quarry applying Completely Randomized Design. The research method used was experimental in disused limestone mining in karst Gombong area applying Completely Randomized Design (CRD). Treatment consisted of 6 planting methods with 4 replicates. The 6 treatments research were the followings: RO: Single planting of dwarf elephant grass, R1: Single planting of dwarf elephant grass + 1.5 kg/m2 goat compost, R2: Mixture Planting of dwarf elephant grass + legume peanuts + 1.5 kg/m2 goat compost, R3: Mixture planting of dwarf elephant grass + legume soybeans + 1.5 kg/m2 goat compost, R4: Mixture planting of dwarf elephant grass + legume cowpeas + 1.5 kg/m2 goat compost and R5: Mixture planting of dwarf elephant grass + legume mung beans + 1.5 kg/m2 goat compost. The measured response variables were plant’s height, fresh yield, dry matter yield and crude protein content of dwarf elephant grass aged 8 weeks. The result showed that the addition of goat compost and the planting method of annual legumes on the disused limestone quarry had highly significant influence (P<0.01) on the increase productivity and quality of dwarf elephant grass. The best method of planting dwarf elephant grass (Pennisetum purpureum cv. Mott) on disused limestone mining in karst Gombong area is mixture planting with soybean legumes (Glycine max) and adding the 1.5 kg/m2 goat compost.