The physical basis for ecohydrologic separation: the roles of soil hydraulics and climate

The degree of water mixing in the critical zone is under intense debate. Field measurements of isotope ratios indicate varying degrees of separation between pools of water that supply streams and vegetation. The exact physical mechanisms behind ecohydrologic separation are unknown, but local conditions such as soil heterogeneities likely influence the extent of mixing and separation of subsurface water pools. Using a well-established soil physics model, we simulated if isotopic separations occur within 650 distinct configurations of soil properties, climatologies, and mobile/immobile soil-water domains. Simulations demonstrated separations in isotope ratios between storage and drainage waters during periods of high precipitation, soil water content, and drainage. Separations grew with larger immobile domains and, to a lesser extent, higher mobile-immobile transfer rates. Across soil types and climates, lower saturated hydraulic conductivity and higher rainfall rates amplified isotopic differences, illustrating how mobile and immobile domains interact with local conditions to physically result in subsurface separations. These results show how different critical-zone solute fluxes can be generated by representing contrasting transport dynamics in distinct domains across a range of soils and climate conditions.

Indeks Kualitas Tanah pada Lahan Pengembangan Kopi Arabika di Kabupaten Bener Meuriah Provinsi Aceh, Indonesia

Abstrak. Provinsi Aceh merupakan sentral utama produksi Kopi arabika yang dikelola secara organik. Dua kabupaten yang mengembangkan kopi arabika organik yaitu Kabupaten Aceh Tengah dan Bener Meuriah yang merupakan dataran tinggi dengan ketinggian 1500 hingga 1900 mdpl. Areal pengembangan kopi organik ini memiliki fisiografi perbukitan dengan jenis tanah yang beragam yang rentan akan terjadinya erosi, sehingga akan berpengaruh terhadap kualitas lahan dan produksi kopi. Penelitian ini bertujuan untuk mengevaluasi dan pemetaan indeks kualitas tanah pada areal perkebunan kopi di Kabupaten Bener Meriah, Provinsi Aceh. Studi ini menggunakan metode survei deskriptif yaitu melalui pengamatan lapangan dan analisis laboratorium. Perhitungan indeks kualitas tanah (IKT) menggunakan kriteria Mausbach dan Seybold (1998) yang telah dimodifikasi Partoyo (2005). Parameter yang dianalisis meliputi karakteristik kimia tanah dan fisika tanah. Hasil penelitian menunjukkan sangat baik (IKT = 0,80 – 1,00). Indeks kualitas tanah pada lahan pengembangan Kopi Arabika di Kabupaten Bener Meuriah, Provinsi Aceh secara umum tergolong baik walaupun nilai SQI antara satuan lahan bervariasi dari sedang hingga tinggi.Soil Quality Index on Arabica Coffee Development Land in Bener Meuriah District, Aceh Province, Indonesia Abstract. Aceh Province is the main center of arabica coffee production and is organically managed. There are two districts that develop organic Arabica coffee, namely Central Aceh and Bener Meuriah districts (altitude 1500-1900 m above sea level). This organic coffee development area has steep physiography with various soil types and is susceptible to erosion, with the result that it will affect the quality of the land and coffee production. This study aims to evaluate a soil map of soil quality index in a coffee plantation area in Bener Meriah Regency, Aceh Province. This study uses a descriptive survey method, namely by field observations and laboratory analysis. Calculation of the soil quality index (SQI) using the criteria of Mausbach and Seybold (1998) and modified by Partoyo (2005). Parameters were analyzed including soil chemical characteristics and soil physics. The results of the soil quality index showed eminent value, namely 0.80 – 1.00. In general, soil quality index on arabica coffee development land in Bener Meuriah Regency is classified as decent although the SQI value between land units varies from moderate to high.

Transition to conservation agriculture: how tillage intensity and covering affect soil physical parameters

Conservation agriculture (CA) relies on two key practices to improve agricultural sustainability—reduced tillage and cover crop usage. Despite known soil physics benefits (reduced soil compaction and strength, enhanced soil porosity and permeability), inconsistent reports on short-term CA results have limited its adoption in European agroecosystems. To elucidate the short-term effects, a three-year experiment in the low-lying Venetian plain (Northern Italy) was undertaken. Bulk density, penetration resistance, and soil hydraulic measures were used to evaluate results obtained by combining three tillage intensities (conventional tillage (CT), minimum tillage (MT), no tillage (NT)) with three winter soil coverages (bare soil (BS), tillage radish cover crop (TR), winter wheat cover crop (WW)). Among the tillage methods and soil layers, CT, on average, reduced BD (1.42 g cm−3) and PR (1.64 MPa) better in the 0–30 cm tilled layer. Other treatments yielded higher values (+4 % BD and +3.1 % PR) in the same layer. Across the soil profile, reduced tillage coupled with WW improved soil physics even below the tilled layer, as evidenced by root growth-limiting threshold declines (−11 % in BD values > 1.55 g cm−3 and −7 % in PR values > 2.5 MPa). Soil hydraulic measures confirmed this positive behaviour; NT combined with either BS or WW produced a soil saturated conductivity of 2.12 × 10−4 m s−1 (four-fold that of all other treatments). Likewise, sorptivity increased in NT combined with BS versus other treatments (3.64 × 10−4 m s−1 vs an all-treatment average of 7.98 × 10−5 m s−1). Our results suggest that despite some measure declines due to reduced tillage, the strategy enhances soil physics. In the short term, cover crop WW moderately increased physical soil parameters, whereas TR had negligible effects. This study demonstrates that CA effects require monitoring several soil physical parameters.

Complementary Teaching Approaches Facilitating Interdisciplinary Soil Science Education

The complementary nature of different teaching approaches in facilitating student learning are rarely discussed in the literature. This study compared diverse teaching approaches in soil science education to explore how a combination of instructional approaches can support student learning. Student perspectives on lectures, problem-based learning, and experiential learning in three upper-level university soil science courses were assessed through student enrolment data and survey responses. Results emphasize the benefits of integrating theory and practice, and support the integration of concepts from soil physics, chemistry and biology within individual courses. All respondents who took two or more courses, indicated that the distinct teaching approaches, and the integration of soil physics, chemistry and biology within individual courses were beneficial to their learning. Lectures and problem-based learning were seen as pedagogically reciprocal, with theory supporting the application of knowledge for 75% students, while others noted that having the management course first, provided context for learning additional theory. A subset of students (n=9) indicated the relevance of the interdisciplinary nature of the courses for their current employment. Our findings suggest that combining knowledge-based and competency-based approaches may support both student learning and workforce demands, and that diverse teaching approaches can work together to support student learning. The research outcomes call for fellow instructors to diverge from the dichotomy of passive and active learning, and to consider the complementary nature of distinct teaching strategies.

Application of Nanoparticle of Merapi Volcanic Ash and Phosphate-Solubilizing Fungi in Improving Inceptisols Characteristics

Nanoparticles of Merapi volcanic ash and phosphate-solubilizing fungi were expected to function as ameliorants in improving some Inceptisols characteristics. Nanoparticles of volcanic ash were used in accelerating and streamlining the chemical reaction in the soil. Phosphate-solubilizing fungi were expected to assist the process of several soil reactions. The aim of the research was to improve some chemical characteristics like available P, cation exchange capacity, Fe, and Zn content of Inceptisols in Cilembu Village, Sumedang District, West Java Province, Indonesia. The research used a complete randomized experimental design in factorial with two factors. The first factor was the nanoparticle of Merapi volcanic ash consisted of four doses on soil weight percentage (0%, 2%, 4%, and 6%). The second factor was phosphate-solubilizing fungi consisted of two doses (without and 10 g.kg-1). The volcanic ash was collected from Mt. Merapi, Central Java, after the eruption of November 2010 and kept in the Laboratory of Soil Physics and Conservation in Faculty of Agriculture, Universitas Padjadjaran. The nanoparticle of volcanic ash was processed at Nanotechnology and Graphene Research Centre, Universitas Padjadjaran. The phosphate-solubilizing fungi were isolated from Inceptisols in Soil Microbiology Laboratory, Universitas Padjadjaran. These treatments were combined and mixed with soils and incubated for three months. Every one month during those three months of the incubation period, some soils were taken to be analyzed of available P, cation exchange capacity (CEC), available Fe, and available Zn. The result showed that there was no interaction between the nanoparticle of Merapi volcanic ash and phosphate-solubilizing fungi to parameters investigated except the CEC after two months of incubation. There was an effect of nanoparticle volcanic ash and phosphate-solubilizing fungi individually to available Fe dan Zn. There was a trend of increasing available P, and CEC and decreasing available Fe and Zn by the longer period of incubation.

Pengujian Cone Index pada Tanah Kering dengan Menggunakan Digital Penetrometer

Persiapan lahan pada budidaya pertanian merupakan salah satu faktor penting pendukung produktivitas pertanian. Tahanan penetrasi tanah dapat digunakan untuk menggambarkan kondisi ketahanan tanah terhadap penetrasi akar. Penelitian ini bertujuan untuk mengetahui hubungan antara kadar air tanah dengan CI menggunakan penetrometer digital. Pengujian penetrasi tanah yang dilakukan pada lahan kering tanpa pengolahan tanah dengan kedalaman 0 – 60 cm. Tekstur tanah yang diuji berdasarkan standar Japanese Soil Physics adalah Loam. Penetrometer yang digunakan termasuk kedalam penetrometer kerucut tipe laju konstan. Terdapat keeratan yang kuat antara CI dan KA, z pada pengujian penetrasi tanah di lahan kering tanpa pengolahan dengan nilai Multiple R sebesar 0.9688. Berdasarkan hasil pengujian ANOVA didapatkan pengaruh KA terhadap CI secara signifikan dan positif.

Produção de biomassa e cobertura do solo pelo consórcio de crotalária e milheto e sua influência em propriedades físicas dos solo

O objetivo neste trabalho foi avaliar a cobertura do solo proporcionada pela crotalária e milheto consorciados em diferentes proporções, bem como seus efeitos na qualidade física do solo. A instalação do experimento obedeceu ao delineamento em blocos casualizados. Os tratamentos foram constituídos de crotalária (Crotalaria spectabilis ) (CR) e milheto (Pennisetum glaucum L. ) (MI) consorciados em diferentes proporções de semeadura, totalizando seis tratamentos: 100% CR (crotalária solteira); 80% CR + 20% MI; 60% CR + 40% MI; 40% CR + 60% MI; 20% CR + 80% MI; 100% MI (milheto solteiro), com quatro repetições. As variáveis avaliadas foram a biomassa seca aos 118 dias após a semeadura, a porcentagem de cobertura do solo e umidade do solo aos 30, 60, 90 e 120 dias após o manejo das plantas, a resistência a penetração até 40 cm e densidade do solo na camada de 0-10. Aos 118 dias após a semeadura, a crotalária, o milheto e seus consórcios produziram quantidade de biomassa seca suficiente para promover a cobertura do solo de em média 77% até os 120 dias após o manejo das plantas, contudo não foram capazes de promover diferenças nos atributos físicos do solo. Palavras-chave: Física do solo. Palhada. Sistema de plantas de cobertura. Biomass production and soil coverage by the crotalary and millette consortium and its influence on physical properties AbstractThe aim of this work was to evaluate the soil cover provided by crotalaria and millet intercropped in different proportions, as well as their effects on the physical quality of the soil. The installation of the experiment followed the randomized block design. The treatments consisted of crotalary (Crotalaria spectabilis) (CR) and millet (Pennisetum glaucum L.) (MI) intercropped in different sowing proportions, totaling 6 treatments: 100% CR (single crotalary); 80% CR + 20% MI; 60% CR + 40% MI; 40% CR + 60% MI; 20% CR + 80% MI; 100% MI (single millet), with 4 repetitions. The variables evaluated were dry biomass at 118 days after sowing, the percentage of soil cover and soil moisture at 30, 60, 90 and 120 days after plant management, the resistance to penetration up to 40 cm and soil density in the 0-10 layer. At 118 days after sowing the crotalary, the millet and their intercropping produced enough dry biomass to promote an average 77% soil cover until 120 days after plant management, however, they were unable to promote differences in the physical attributes of the soil. Keywords: Soil physics. Straw. Cover plants system.

Using data assimilation to optimize pedotransfer functions using field-scale in situ soil moisture observations

Soil moisture predictions from land surface models are important in hydrological, ecological, and meteorological applications. In recent years, the availability of wide-area soil moisture measurements has increased, but few studies have combined model-based soil moisture predictions with in situ observations beyond the point scale. Here we show that we can markedly improve soil moisture estimates from the Joint UK Land Environment Simulator (JULES) land surface model using field-scale observations and data assimilation techniques. Rather than directly updating soil moisture estimates towards observed values, we optimize constants in the underlying pedotransfer functions, which relate soil texture to JULES soil physics parameters. In this way, we generate a single set of newly calibrated pedotransfer functions based on observations from a number of UK sites with different soil textures. We demonstrate that calibrating a pedotransfer function in this way improves the soil moisture predictions of a land surface model at 16 UK sites, leading to the potential for better flood, drought, and climate projections.