Hairy vetch (Vicia villosa), as a winter cover crop, can be used to suppress weeds in subtropical regions, as well as temperate regions. Information on the potential biomass growth of hairy vetch for weed control and nutrient accumulation is not available in subtropical regions. Hairy vetch was sown in November 2004, and October, November, and December 2005. The wide‐ranging cultivation period of hairy vetch indicated that it could be used in various cropping systems. It showed a higher biomass and nutrient accumulation when grown in subtropical Okinawa, Japan. Moreover, the biomass, and fixed carbon and magnesium (Mg) uptake in the above‐ground parts of hairy vetch were found to be the highest in late May, with the highest nitrogen (N), potassium, and calcium uptake in mid‐April and phosphorus (P) uptake in late March. Meanwhile, in the underground parts of the plant, they were highest in early May, except for the P and Mg uptake, which were highest in mid‐April. According to the sowing date, the biomass and nutrient uptake of hairy vetch that was harvested in February were higher when sown in October. Similarly, when harvested in March, the biomass and nutrient uptake were higher when sown in October or November. In April, they were higher when sown in November or December. Hairy vetch has the potential to effectively suppress weeds in the winter and the spring seasons related to its sufficient biomass during the growing seasons. However, both the sowing and harvesting times of hairy vetch should be considered with reference to the cropping system; the subsequent crop will be sown to meet the N requirement.

No abstract

Weeds emerge throughout the year in agricultural fields in subtropical regions. The weed suppression and improved soil fertility resulting from a living mulch of hairy vetch were investigated. Hairy vetch was sown in October and in December 2006. The fallow condition was without the sowing of hairy vetch, with the weeds allowed to grow naturally. The biomass of the top parts (BOT) of hairy vetch increased from February to April and then decreased in May on both sowing dates. The BOT of hairy vetch sown in October was significantly higher in February, March, and April than that sown in December. Hairy vetch sown in October and harvested from February to April varied from 372–403 × 10−3 kg m−2, with weed suppression percentages of 62.8% in comparison with the fallow plots. The fixed C, N, P, and mineral uptake of hairy vetch showed similar patterns to its biomass. The nitrate (NO3‐N) content increased from February to May for the soils in the October and December plots, in contrast to the fallow plots. Moreover, the NO3‐N and available N of the October and December soils sampled from February to May were higher than that of the fallow soils. In subtropical agriculture, hairy vetch should be sown in October in order to achieve a higher biomass for suppressing weeds effectively and improving the soil fertility, mainly N.

No abstract

Penggunaan deterjen dalam laundry yang meningkat seiring perubahan gaya hidup dan sosialekonomi menghasilkan limbah laundry yang dapat menimbulkan dampak pencemaran air akibat berlebihnya kadar fosfat di perairan. Metode kolom adsorpsi merupakan salah satu cara mengolah air limbah laundry. Penelitian dilaksanakan untuk mengetahui pengaruh variasi aliran, waktu dan kolom terhadap suhu, pH, warna dan konsentrasi fosfat; serta mengetahui pengaruh kombinasi granular activated carbon (GAC) berbahan dasar tempurung kelapa dalam kolom terhadap removal fosfat. Kolom adsorpsi dijalankan dengan aliran non-sirkulasi (NS) dan sirkulasi (S). Media adsorpsi adalah GAC 4x8 mesh (11.3 mm 2) 200 gram (K1); GAC 4x8 mesh 300 gram (K2); GAC 6x12 mesh (5.6 mm 2) 200 gram (K3) dan; GAC 6x12 mesh 300 gram (K4). Pengambilan sampel dilakukan setiap 60 menit sekali selama 3 jam. Peningkatan suhu terjadi pada kolom NS dan penurunan suhu terjadi pada kolom S saat waktu retensi 60-180 menit. Penurunan pH terjadi pada semua kolom dengan semua jenis aliran selama proses. Warna air meningkat pada waktu retensi 180 menit, dimana warna air berubah dari gelap menjadi transparan. Peningkatan konsentrasi fosfat terjadi pada kolom NS dan penurunan konsentrasi fosfat terjadi pada kolom S saat waktu retensi 60-180 menit. Kolom terbaik dalam menyisihkan fosfat adalah kolom K4 dimana mampu menghilangkan kadar fosfat sebanyak 70.79-74.68%. Konsentrasi fosfat berkorelasi positif sedang (R 2 = 0.49) terhadap suhu dan berkorelasi positif lemah (R 2 = 0.14) terhadap pH selama proses.