Organic phosphorus (P) plays an important role in the soil P cycle. It is present in various chemical forms, the relative amounts of which vary among soils, due to factors including climate, land use, and soil type. Few studies have investigated co-variation between P types or stoichiometric correlation with the key elemental components of organic matter– carbon (C) and nitrogen (N), both of which may influence P pool structure and dynamics in agricultural soils. In this study we determined the organic P speciation of twenty Australian Red Chromosols soils, a soil type widely used for cropping in Australia. Eight different chemical forms of P were quantified by 31P NMR spectroscopy, with a large majority (>90%) in all soils identified as orthophosphate and humic P. The strongest correlations (r2 = 0.77–0.85, P < 0.001) between P types were found among minor components: (i) between two inositol hexakisphosphate isomers (myo and scyllo) and (ii) between phospholipids and RNA (both detected as their alkaline hydrolysis products). Total soil C and N were correlated with phospholipid and RNA P, but not the most abundant P forms of orthophosphate and humic P. This suggests an influence of organic matter content on the organic P pool consisting of phospholipid and RNA, but not on inositol P or the largest organic P pool in these soils – humic P.

AbstrakDesa Oelbiteno merupakan salah satu desa dari empat desa yang ada di Kecamatan Fatuleu Tengah yang merupakan salah satu tempat wisata alam di Kab. Kupang-NTT. Daerah ini memiliki potensi pengembangan agroekowisata. Namun sistem pertanian rakyatnya masih bersifat konvensional. Karena itu, untuk peningkaan pertumbuahan eknomi desa dan masyarakat perlu adanya alih guna lahan dari pertanian campuran subsistem menjadi agroekowisata. Diikuti oleh peningkatan produktivitas lahan melalui perbaikan pola tanam lahan kering sesuai kearifan lokal. Kegiatan ini adalah pemberdayaan masyarakat melalui desain kebun model pertanian lahan kering, membimbing dan mendampingi petani agar usaha taninya dapat bernilai ekonomis dan mempunyai dampak ekologi yang baik. Dengan memanfaatkan beberapa objek alam (mata air dan kolam), produk pertanain lahan kering dengan pola tanam bedengan sejajar kontur, dan aplikasi pertanian organik berbahan local dengan pendekatan circular economy telah menambah pemahaman, sikap dan ketrampilan dalam rangka upaya perbaikan pertanian lahan kering yang sehat dan berkelanjutan.Kata Kuncicircular economy, pertanian organik, pola tanam lahan kering

Mamar is a traditional agroforestry system established many years ago on Timor Island. It can maintain water reservoirs, natural habitat, and ecology conservation to support the livelihoods of local people. Although, Mamar is a symbol of heritage, “people will not leave it, but also do not want to see it” an unmanaged system. This study aims to understand the challenges and potential developments of the Mamar. A study on ecosystem services and the potential sustainability of Mamar was conducted in Ponain village using four sampling locations. Data was collected from observation, focus group discussion, laboratory analysis, and secondary data. The results showed that the change of land use from agroforestry to monoculture had reduced the quality of topsoil, water, and the biodiversity of local plants. Mamar could provide good services for the ecosystem, but we are unsure if it can be sustained because the youth tend to leave the Mamar. However, it seems likely this heritage can survive with strong partnership from Pentahelix collaboration (government, education, business, community, and media), applying multifunctional ecosystem (Agro ecotourism and community-based tourism), and eventually creating a business model. This collaboration will help to improve ecosystem and economic services, as well as rural development.

Phosphorus-31 nuclear magnetic resonance ( 31 P NMR) spectroscopy is widely used to identify and quantify phosphorus (P) forms in soil. This study aimed to determine whether narrowing the soil to extractant sodium hydroxide-ethylenediaminetetraacetic acid (NaOH-EDTA) ratio from 1:20 to values as low as 1:4 would improve sensitivity of solution 31 P NMR spectroscopy without degrading resolution or quantitation. Four Australian soils were tested using four ratios. The narrowest ratio of 1:4 gave the best quality NMR spectra in terms of signal-to-noise ratio. Peak resolution was not degraded on narrowing the ratio. There was no clear effect of narrowing the extraction ratio on extraction efficiency or the distribution of signal among chemical shift regions (orthophosphate, monoester P, diester P, and pyrophosphate). We conclude that a ratio of 1:4 improved NMR analysis for these particular soils and should be considered for other soils, particularly low-P soils, where NMR sensitivity is limiting.