Soil and Water Conservation Engineering

Skip to main page content HOME CURRENT ISSUE ARCHIVE FEEDBACK SUBSCRIPTIONS ALERTS HELP Keywords Search Advanced »User Name Password Sign In Modeling phosphorus transport in agricultural watersheds: Processes and possibilities A. N. Sharpley, P. J. A. Kleinman, R. W. McDowell, M. Gitau, and R. B. Bryant ABSTRACT: Modeling phosphorus (P) loss from agricultural watersheds is key to quantifying the long term water quality benefits of alternative best management practices. Scientists engaged in this endeavor struggle to represent processes controlling P transport at scales and time frames that are meaningful to farmers, resource managers, and policy makers. To help overcome these challenges, we reviewed salient issues facing scientists that model P transport, providing a conceptual framework from which process-based P transport models might be evaluated. Recent advances in quantifying the release of soil P to overland and subsurface flow show that extraction coefficients relating soil a...

The use of biochar can improve the various soil properties and reduce erosion. Also, biochar production has caused the optimal use of agricultural and industrial waste and can convert waste into useful compounds. A large mass of leaves and pruned barberry and jujube branches are abandoned annually without planning to use in South Khorasan. Therefore, in this experiment, the impact of biochars produced from barberry and jujube pruned materials (after six months) on the rate of soil erosion, nutrient, and soil properties were studied in the laboratory conditions at the University of Birjand, Iran, in 2021. Biochar treatments were examined at three 0%, 2%, and 5% levels by weight with four replications. Physicochemical and biological properties and soil nutrients were measured before and after adding biochars and applying erosion. The amount of soil loss was calculated by a standard portable rainfall simulator (a rainfall with an intensity of 160 mm/h for 15 min). The data was investigated using variance analysis and mean comparison (by LSD test and P ≤ 0.05), based on a completely randomized design by JMP13 software. The H/C ratio in the barberry and jujube biochars was about 0.33 and 0.53, respectively. Using the biochars at the 2% and 5% application levels significantly decreased soil erosion and improved soil properties. The 5% barberry biochar treatment caused the greatest reduction in bulk density and soil loss. Moreover, this treatment greatly increased the mean weight diameter of aggregates, saturation moisture, cation exchange capacity, organic matter, microbial biomass carbon, microbial respiration, and substrateinduced respiration of the soil compared to the other treatments. It was also more efficient in increasing and retaining soil nutrients. Using the produced biochars is recommended to improve the soil properties.

Mulugetta Mekuria is a senior scien-tist with the Socioeconomics Program, based at the International Maize and Wheat Improve-ment Centre (CIMMYT) Southern Africa Regional Office based in Harare, Zimbabwe. Christian Thierfelder is a conservation agriculture specialist with CIMMYT Southern Africa Regional Office based in Harare, Zimbabwe. Abstract: Understanding factors affecting farmers' adoption of improved technologies is crit-ical to success of conservation agriculture (CA) program implementation. This study, which explored the factors that determine adoption and extent of farmers' use of the three principles of CA (i.e., minimum soil disturbance, permanent soil cover with crop residues, and crop rotations), was conducted in 10 target communities in 8 extension planning areas in Malawi. The primary data was collected using structured questionnaires administered to individual households. Triangulation with key informant interviews, field observations, and interactive discus...

Watershed erosion is a cause of nonpoint source pollution that can have an adverse effect on downstream and ecosystem water quality. Three different approaches using geographical information systems (GIS) and digital elevation models (DEMs) are described and evaluated for applying the Water Erosion Prediction Project (WEPP) model to assess water erosion in small watersheds. The first approach describes a typical application of the watershed version of WEPP using GIS only as an aid for construction of required input files. The second approach presents an automated method for the application of WEPP through the extraction of hillslopes and channels from DEMs. The third approach was WEPP model simulations on all possible flowpaths within a watershed. The three methods were applied to six research watersheds: one from Treynor, IA, two from Watkinsville, Ga., and three from Holly Springs, Miss. A statistical analysis for all methods and watersheds compared the predicted vs. measured runo...

Abstract: Outlined is a practical approach to size and modify agricultural drainage channels to two-stage geometry to maintain drainage function and capacity while increasing chan-nel stability. Two-stage channel systems consist of an inset channel and small floodplain ( ...

Background. China is the leading consumer of plastic film worldwide. Plastic film mulched ridge-furrow is one of the most widely adopted agronomic and field management practices in rain-fed agriculture in dry-land areas of China. The efficiency of plastic film mulching as a viable method to decrease evapotranspiration (ET), increase crop yields, and water use efficiency (WUE), has been demonstrated extensively by earlier studies. Methods. A comprehensive evaluation of how co-application of plastic-film mulch and biochar in different agro-environments under varying climatic conditions influence ET, crop yield, WUE, and soil microbial activity were assessed. We performed a meta-analysis using the PRISMA guideline to assess the effect of plastic-film mulched ridge-furrow and biochar on ET, yield, and WUE of wheat (Triticum aestivum L.), potato (Solanum tuberosum L.), and maize (Zea mays L.) in northern China. Results. The use of plastic film increased average yields of wheat (75.7%), potato (20.2%), and maize (12.9%) in Gansu, Ningxia, Shaanxi, and Shanxi provinces, respectively due to the reduction in ET by 12.8% in Gansu, 0.5% in Ningxia, and 4.1% in Shanxi, but increased in Shaanxi by 0.5% compared to no-mulching. These changes may be attributed to the effect of plastic film mulch application which simultaneously increased WUE by 68.5% in Gansu, 23.9% in Ningxia, 16.2% in Shaanxi, and 12.8% in Shanxi, respectively. Compared to flat planting without mulching, in three years, the yield of maize increased with the co-application of plastic film and biochar by 22.86% in the Shanxi and Shaanxi regions. Conclusion. Our analysis revealed co-application of plastic film with biochar is integral for improving soil and water conservation in rain-fed agriculture and as an integrated practice to avert drought while simultaneously mitigating runoff and erosion.

Ten soil sites in western Kansas sampled in 1948 were resampled in 1984 to compare the particle size distribution (texture) and organic matter content in the top 10 cm. Except at one site, the sand fraction increased; this increase ranged from 0.9 to 23.3 percentage points. The greatest changes occurred in the moderately coarse and coarse tex-tured (sandy) soils. Overall changes in particle distribution were + 6.5, -7.2, and + 0.7 percentage points for sand, silt, and clay, respectively, indicating that silt was removed through sorting by wind. Organic matter declined at 8 of the 10 sites, averaging about 19 % overall OT about 0.01 percentage points per year. Erosion or other factors are caus-ing a slow decline in silt content and organic matter in these soils, with potentially detri-mental effects on soil structure, nutrient availability, and water-holding capacity. VER time wind erosion sorts soil,

Efficiencies of surface irrigation systems are often limited by infiltration conditions. Treatments that decrease infiltration into unlined canals, reservoirs, and the inflow end of furrows relative to outflow ends would reduce seepage losses and improve application uniformity. Several laboratory studies evaluated effects of high molecular weight (10 to 15 Mg mol-1), water-soluble, anionic polyacrylamide (PAM), alone and combined with anionic surfactants, on the hydraulic conductivity (KSAT) of soils. Dry soils were treated with one or two treatment solutions and subjected to conditions that simulated those in an irrigation furrow or pond. The KSAT of soil packed in columns was measured with a constant head apparatus for 19 hours. PAM treatment concentrations > 125 mg L-1 applied to dry soils preceding flooding reduced KSAT by 25%, and a 10 mg-L-1 PAM + 29 k-mg-L-1 sodium-lauryl-sulfate surfactant application reduced KSAT by 70%, relative to controls. Miniflume tests then applied...

Residential households have the potential to conserve water, especially in behaviourally influenced end uses such as showering. Visual display monitors detailing shower water consumption parameters provide householders with a better understanding of their water use consumption and serve as a prompt to conserve. This longitudinal study first applied high resolution smart meters to create a registry of shower end use event parameters (i.e. shower duration, flow rate and duration) before and after the introduction of an alarming visual display monitor. The study showed a statistically significant mean reduction of 15.40 L (27%) in shower event volumes shortly after the implementation of the shower monitor. However, two subsequent smart metering reads indicated that shower end use water consumption savings diminished over time and mean showering volumes reverted back to their pre-intervention level after 4 months. That is, the longitudinal study provides empirical evidence that technological devices informing resource consumption may not be effective unless instilled habits or attitudes can be also modified; old habits die hard. Follow-up questionnaire surveys allowed for qualitative interpretations of the behavioural findings, through demographic summaries, residents' perceptions on shower monitor performance and their use of device over time, to name a few.

Current algal-bacterial consortia require hydraulic retention times (HRTs) of up to 2-10 days for wastewater treatment. The application of a photo membrane bioreactor (PMBR) culturing an algal-bacterial consortium should significantly reduce the HRTs, which has not been attempted before. A low light intensity, 200 μmol/ (m 2 ·s), was applied in a PMBR. The results showed that ammonium was almost completely removed and the removal efficiency of chemical oxygen demand was 90% when the HRT was as low as 24 h and mechanical aeration was not applied. Ammonium-oxidizing bacteria and algae approximately equally shared the ammonium in the reactor. Phosphate reduction was approximately 3 mg PO 4 3−-P/L.h. A light intensity of up to 600 μmol/ (m 2 ·s) did not inhibit algal activity. The complete removal of ammonium resulted in a decline in the chlorophyll a concentration. Nevertheless, the reactor performance remained stable. Heterotrophic bacteria, autotrophs, algae and phosphate-accumulating organisms coexisted and functioned in the reactor. Furthermore, a sustainable flux of 15 L/m 2 .h enabled operating the filter of the PMBR at a transmembrane pressure as low as 4 kPa. Considering the stable pollutant removal performance and significant reduction in HRT, this PMBR has the potential to be applied in wastewater treatment.