Search

To address the need for information on biochar effects on crop growth and nitrogen (N), a greenhouse study was conducted with carrot, lettuce, soybean, and sweet corn using sandy loam (Coxville series) and loamy sand (Norfolk series) soils and a variety of biochars. Biochar was produced from pine chips (PC), poultry litter (PL), swine solids (SS), switchgrass (SG), and two blends of PC plus PL (50/50% [55] and 80/20% [82], wt/wt), with each feedstock pyrolyzed at 350, 500, or 700 ˚C. The results confirmed that biochar can increase crop growth; however, the responses varied with crop, soil, and feedstock and to a lesser extent with pyrolysis temperature. In general, lettuce had large increases in shoot and root dry weights vs. no‐biochar controls with many biochars, primarily the SS and 55 blend and to a lesser extent with 82 followed by PL, and then PC and SG, especially when grown in the Coxville soil. Biochar had more limited effects on carrot, sweet corn, and soybean weights. Some biochars decreased crop growth (e.g., PL at 700 ˚C) for soybean shoot and pod dry weights with the Norfolk soil. Shoot N concentrations decreased with SS, 55, and 82 for carrot, lettuce, and sweet corn with the Norfolk soil but tended to increase for soybean. Shoot N uptake increased or decreased depending on biochar feedstock and temperature, crop, and soil. These results confirm that biochar can increase crop growth and affect shoot N, which is essential for crop growth.

Conservation agriculture practices have been widely implemented to improve soils and their sustainability. Here, we investigated the impacts of long-term conservation tillage (CS) on soil aggregate...

The application of designer biochar has the potential to impact soil enzyme activity and soil nitrogen dynamics. However, very little is known about the mechanisms responsible for biochar-enzyme-nitrogen interaction in highly weathered soils. The objective of our 3-year (2016–2018) field experiment was to evaluate the effectiveness of designer biochars (DB) in enhancing urease activity (UA), total nitrogen (TN), total inorganic nitrogen (TIN), and nitrogen uptake (NU) at different growth stages (GS) of corn in a highly weathered soil of southeastern Coastal Plain region, USA. Experimental treatments have consisted of the control, 100% pine chips (100PC), 100% poultry litter (100PL), 2:1 blend of PC and PL (PCPL), 100% raw switchgrass (Panicum vaginatum, L; 100RSG), and 2:1 blend of PC and RSG (PCRSG). All the designer biochar treatments were applied at the rate of 30,000 kg ha−1 to a Goldsboro loamy sand in 2016. Urease activity, TN, TIN, and NU varied remarkably with DB (p ≤ 0.0001) at different GS (p ≤ 0.0001) of corn. Soils treated with 100PL had the greatest UA (28.18 µg N g−1 h−1), TN (0.087%), and TIN (14.53 mg kg−1) while the least UA, TN, and TIN of 20.55 µg N g−1 h−1, 0.063%, and 5.42 mg kg−1, respectively, were observed from the control. The three-year TN average increase over the control was in the order: 100PL (36.8%) > 100RSG (25.8%) > PCRSG (25.3%) > PCPL (23.9%) > 100PC (7.1%). The greatest NU of corn of 140.4 kg N ha−1 was from soils treated with 100PL while the least amount of NU was from 100PC. Overall, our results showed promising significance for the treatment of highly weathered soils since the application of DB did enhance UA and improve TN and TIN in the soils.

Essential nutrient concentrations in crops can affect human health. While biochar has the potential as a soil amendment to improve crop yields, it may also affect the concentrations of nutrients such as Ca, Fe, K, Mg, Mn, and Zn in edible portions of crops. To better characterize effects of biochar on important human nutrients in food crops, we evaluated the effects of biochar on lettuce (Lactuca sativa L. cv. Black-Seeded Simpson) leaf and carrot [Daucus carota subsp. sativus (Hoffm.) Schübl. cv. Tendersweet] developing taproot nutrients. Plants were grown in pots in a greenhouse using sandy loam (Coxville, fine, kaolinitic, thermic Typic Paleaquults) and loamy sand (Norfolk, fine-loamy, kaolinitic, thermic Typic Kandiudults,) series soils, amended with biochar produced from four feedstocks: pine chips (PC), poultry litter (PL), swine solids (SS), and switchgrass (SG); and two blends of PC plus PL [PC/PL, 50%/50% (55) and 80%/20% (82) by weight]. Biochar was produced at 350, 500, and 700 °C from each feedstock. Lettuce leaf and carrot taproot total nutrient concentrations were determined by inductively coupled plasma analysis. Biochar (especially at least in part manure-based, i.e., PL, SS, 55, and 82 at nearly all temperatures) primarily decreased nutrient concentrations in lettuce leaves, with Ca, Mg, and Zn affected most. Carrot taproot nutrient concentrations also deceased, but to a lesser extent. Some biochars increased leaf or taproot nutrient concentrations, especially K. This study indicated that biochar can both decrease and increase leaf and taproot nutrient concentrations important for human health. Thus, potential effects on nutrients in plants should be carefully considered when biochar is used as a soil amendment with vegetable crops.

The Oronogo-Duenweg mining belt is a designated United States Environmental Protection Agency Superfund site due to lead-contaminated soil and groundwater by former mining and smelting operations. Sites that have undergone remediation – in which the O, A, and B horizons have been removed alongside the lead contamination – have an exposed C horizon and are incalcitrant to revegetation efforts. Soils also continue to contain quantifiable Cd and Zn concentrations. In order to improve soil conditions and encourage successful site revegetation, our study employed three biochars, sourced from different feedstocks (poultry litter, beef lot manure, and lodge pole pine), at two rates of application (2.5%, and 5%), coupled with compost (0%, 2.5% and 5% application rates). Two plant species - switchgrass (Panicum virgatum) and buffalograss (Bouteloua dactyloides) – were grown in the amended soils. Amendment of soils with poultry litter biochar applied at 5% resulted in the greatest reduction of soil bioavailable Cd and Zn. Above ground biomass yields were greatest with beef lot manure biochar applied at 2.5% with 5% compost, or with 5% biochar at 2.5% and 5% compost rates. Maximal microbial biomass was achieved with 5% poultry litter biochar and 5% compost, and microbial communities in soils amended with poultry litter biochar distinctly clustered away from all other soil treatments. Additionally, poultry litter biochar amended soils had the highest enzyme activity rates for β-glucosidase, N-acetyl-β-D-glucosaminidase, and esterase. These results suggest that soil reclamation using biochar and compost can improve mine-impacted soil biogeophysical characteristics, and potentially improve future remediation efforts.

Potential new sources of phosphorus (P) fertilizer are the recovered P from livestock wastewater through chemical precipitation and the ash from combusting animal manures. Although most of the research on P losses from conservation tillage include high water-soluble P compounds from commercial fertilizer sources, information on the use of non-conventional, low water-soluble, recycled P sources is scarce. Particularly for sandy soils of the United States (US) Southeastern Coastal Plain region, research driven information on P loss into the environment is needed to determine recommendations for a direct use of new recycled P sources as crop P fertilizers. The objective of this study is to investigate the potential P runoff from sandy soils under conservation tillage, fertilized with recovered P from liquid swine manure and turkey litter ash in comparison with commercial P fertilizer triple superphosphate (TSP). The field study included two typical sandy soils of the US Southeastern Coastal Plain region, the Noboco and Norfolk. Simulated rain corresponding to the annual 30-min rainfall in the study site (Florence County, South Carolina) was applied to plots treated with recovered P from liquid swine manure, turkey litter ash, and TSP, including a control with no P added. The runoff was monitored and sampled every 5 min during the test and composite soil samples were collected from the top (0-15 cm) and subsurface (15-30 cm) soil layers in each plot. Laboratory analyses were conducted to quantify both total P (TP) and soluble reactive P (SRP) in runoff samples, and the soil test P in the soil layers. Two-way analyses of variances show significant treatment effects on both TP and SRP runoff. The quantities of SRP runoff from plots treated with the recovered P from swine manure and turkey litter ash represent respectively 1% and 7-8% of SRP runoff from plots treated with TSP. Hence, the use of the recovered P materials as crop P fertilizers through surface broadcast application present less environmental risks compared to commercial TSP.

Biochar is being considered a climate change mitigation tool by increasing soil organic carbon contents (SOC), however, questions remain concerning its longevity in soil. We applied 30,000 kg ha−1 of biochars to plots containing a Goldsboro sandy loam (Fine-loamy, siliceous, sub-active, thermic Aquic Paleudults) and then physically disked all plots. Thereafter, the plots were agronomically managed under 4 years (Y) of continuous corn (Zea Mays, L.) planting. Annually, incremental soil along with corresponding bulk density samples were collected and SOC concentrations were measured in topsoil (down to 23-cm). The biochars were produced from Lodgepole pine (Pinus contorta) chip (PC) and Poultry litter (PL) feedstocks. An untreated Goldsboro soil (0 biochar) served as a control. After four years, SOC contents in the biochar treated plots were highest in the top 0–5 and 5–10 cm depth suggesting minimal deeper movement. Declines in SOC contents varied with depth and biochar type. After correction for SOC declines in controls, PL biochar treated soil had a similar decline in SOC (7.9 to 10.3%) contents. In contrast, the largest % SOC content decline (20.2%) occurred in 0–5 cm deep topsoil treated with PC biochar. Our results suggest that PC biochar had less stability in the Goldsboro soil than PL biochar after 4 years of corn grain production.

Coastal Plain soils of the southeastern United States are highly degraded, with low soil organic carbon (C), meager soil fertility, and poor soil structure. We tested the effectiveness of clay soil amendment to promote the formation of soil aggregates, improve organic C stability, and enhance nutrient availability in field. Subsurface clay soils (B horizon, 25% clay) were applied (∼25 T ha–¹) to the top of the soil surface, followed by the planting of winter cover crop mixtures. Crop growth and nutrient uptake and relevant soil biogeochemical properties were analyzed at the end of the winter season. Additions of subsurface clay soils prompted the formation of water-stable macroaggregates (250–2000 mm) from 32 to 54% and increased mean weight diameter of the aggregates from 390 to 592 mm. Additions of subsurface clay soils increased clay content from 1.5 to 3.8% but did not change soil texture, pH, water holding capacity, and bulk density. The stock of dissolved organic nitrogen was not affected by the amendment, whereas nitrate leaching from field was reduced by 61% because of clay soil application. Clay soil additions inhibited the activities of C-cycling (N-acetyl-β-glucosaminidase, β-d-cellubiosidase, β-glucosidase, and β-xylosidase) and N-cycling (leucine aminopeptidase) enzymes but did not modify soil microbial community level substrate utilization patterns, resulting in a 63% reduction in C turnover rate and 19% increases in concentrations of labile organic C. Our results indicated that subsurface clay soil amendment can improve soil structure, nutrient availability, and the stability of labile C in the field, at least in the short term, and may be a promising management alternative to enhance the productivity and sustainability of the degraded Coastal plain soils.

Biochar can reduce both nitrous oxide (N2O) emissions and nitrate (NO3-) leaching, but refining biochar's use for estimating these types of losses remains elusive. For example, biochar properties such as ash content and labile organic compounds may induce transient effects that alter N-based losses. Thus, the aim of this meta-analysis was to assess interactions between biochar-induced effects on N2O emissions and NO3- retention, regarding the duration of experiments as well as soil and land use properties. Data were compiled from 88 peer-reviewed publications resulting in 608 observations up to May 2016 and corresponding response ratios were used to perform a random effects meta-analysis, testing biochar's impact on cumulative N2O emissions, soil NO3- concentrations and leaching in temperate, semi-arid, sub-tropical, and tropical climate. The overall N2O emissions reduction was 38%, but N2O emission reductions tended to be negligible after one year. Overall, soil NO3- concentrations remained unaffected while NO3- leaching was reduced by 13% with biochar; greater leaching reductions (>26%) occurred over longer experimental times (i.e. >30 days). Biochar had the strongest N2O-emission reducing effect in paddy soils (Anthrosols) and sandy soils (Arenosols). The use of biochar reduced both N2O emissions and NO3- leaching in arable farming and horticulture, but it did not affect these losses in grasslands and perennial crops. In conclusion, the time-dependent impact on N2O emissions and NO3- leaching is a crucial factor that needs to be considered in order to develop and test resilient and sustainable biochar-based N loss mitigation strategies. Our results provide a valuable starting point for future biochar-based N loss mitigation studies.

Site-specific variable-rate irrigation (VRI) systems can be used to spatially manage irrigation within sub-field-sized zones and optimize spatial water use efficiency. The goal of the research is to provide farmers and consultants a tool to evaluate the potential benefits of implementing VRI. The specific objective of this research is to evaluate the potential water savings using VRI management compared with uniform irrigation management to maintain soil water holding capacity above 50% depletion using two irrigation scenarios: 1) a standard 12.5 mm irrigation per application; and 2) an application to refill the soil profile to field capacity. A 21-year simulation study was carried out on a selected field with varying degrees of soil and topographic variability. The simulated field had 12 soil mapping units with water holding capacities in the top 0.30-m ranging from 42 to 70 mm. The 21-year simulation covering all weather conditions for each soil produced only two significantly different irrigation management zones for scenario 1, and for scenario 2 only one management zone. However, when the 21-year period was divided into periods with different ratios of rainfall to reference evapotranspiration, the simulations identified 1 to 5 management zones with significantly different irrigation requirements. These results indicate that variable rate irrigation system design and management should not be solely based on long term average weather conditions. Years with differing weather conditions should be used for potentially identifying management zones for VRI systems. Irrigation application depths between management zones ranged from 17 to 38 mm. However, when the actual soil areas of the study field were utilized to calculate the total volume of irrigation water applied, it resulted in an increase in water usage in the 2 and 4 management zones ranging from -1.2% to 5.8%. Water usage with VRI over uniform irrigation was greater by -1.6% to 6.8% in the 12.5 mm irrigations and by -1.2% to 2.2% for the field capacity irrigations Keywords: Management zones, Precision farming, Variable-rate irrigation, Water conservation.

Biochars are used for soil fertility improvement because they may contain certain elements that plants use as nutrients. However, few studies have demonstrated enhanced crop nutrient uptake. Our study examined nutrient uptake responses of corn (Zea Mays L.) grain and stover over 4 years (Y) after a Goldsboro sandy loam (fine-loamy, siliceous, sub-active, thermic Aquic Paleudults) received different designer biochars and a compost. The designer biochars were produced from lodgepole pine (Pinus contorta) chip (PC), poultry litter (PL), blends with switchgrass (SG, Panicum virgatum), and a SG compost alone. Topsoil treated with 100% PL biochar and blended PC:PL biochar had significantly greater Mehlich 1 (M1) extractable P, K and Na contents compared to the control or other treatments. No significant differences were detected in annual grain nutrient concentrations. In the first corn stover harvest (Y1), significantly greater concentrations of P and K were taken up after treatment with 100% PL biochar, with PC:PL blend and with SG when compared to control. By the fourth corn stover harvest (Y4), nutrient uptake between treatments was not significantly different. Biochar impact on corn stover P, K and Na concentrations was time dependent, suggesting that repeated biochar applications may be needed.

Potential new sources of phosphorus (P) fertilizers are the recovered P from livestock wastewater through chemical precipitation and the ash from combusting animal manures. These P-rich materials have low water solubility. Most of the research on P losses from conservation tillage include commercial fertilizer sources that have a high-water soluble P content but information on the use of non-conventional, low water soluble, recycled P sources is scarce. The objective of this study was to investigate the potential P runoff from conservation tillage fertilized with phosphates recovered from turkey litter ash and liquid swine manure in comparison with commercial P fertilizer triple superphosphate (TSP). Simulated rain corresponding to the annual 30-minute rainfall in the study site (Florence, South Carolina) was applied to plots treated with three P fertilizer sources and one control. The P fertilizer sources included turkey litter ash (a bio-energy byproduct), granulated recovered P from liquid swine manure, and TSP. The runoff was monitored and sampled every 5 minutes during the test. Laboratory analyses were conducted to quantify the P wash-off in runoff samples. Results show that the quantity of P wash-off from the plots treated with turkey litter ash and the recovered P from swine manure were respectively 10 and 15 times lower than the triple super phosphate plots. These results sustain the use of the turkey litter ash and recovered P from swine manure as crop P fertilizer through surface broadcast application.

Traditionally, livestock manure has been used to provide nutrients for plant growth and to improve soil conditions [...]

Various studies have established that feedstock choice, pyrolysis temperature, and pyrolysis type influence final biochar physicochemical characteristics. However, overarching analyses of pre-biochar creation choices and correlations to biochar characteristics are severely lacking. Thus, the objective of this work was to help researchers, biochar-stakeholders, and practitioners make more well-informed choices in terms of how these three major parameters influence the final biochar product. Utilizing approximately 5400 peer-reviewed journal articles and over 50,800 individual data points, herein we elucidate the selections that influence final biochar physical and chemical properties, total nutrient content, and perhaps more importantly tools one can use to predict biochar's nutrient availability. Based on the large dataset collected, it appears that pyrolysis type (fast or slow) plays a minor role in biochar physico- (inorganic) chemical characteristics; few differences were evident between production styles. Pyrolysis temperature, however, affects biochar's longevity, with pyrolysis temperatures>500 degrees C generally leading to longer-term (i.e.,>1000 years) half-lives. Greater pyrolysis temperatures also led to biochars containing greater overall C and specific surface area (SSA), which could promote soil physico-chemical improvements. However, based on the collected data, it appears that feedstock selection has the largest influence on biochar properties. Specific surface area is greatest in wood-based biochars, which in combination with pyrolysis temperature could likely promote greater changes in soil physical characteristics over other feedstock-based biochars. Crop- and other grass-based biochars appear to have cation exchange capacities greater than other biochars, which in combination with pyrolysis temperature could potentially lead to longer-term changes in soil nutrient retention. The collected data also suggest that one can reasonably predict the availability of various biochar nutrients (e.g., N, P, K, Ca, Mg, Fe, and Cu) based on feedstock choice and total nutrient content. Results can be used to create designer biochars to help solve environmental issues and supply a variety of plant-available nutrients for crop growth. This work was partially supported by the USDA/NIFA Interagency Climate Change Grant Proposal number 2014-02114 [Project number 6657-12130-002-08I, Accession number 1003011] under the Multi-Partner Call on Agricultural Greenhouse Gas Research of the FACCE-Joint Program Initiative. The German BLE and FACCE-JPI funded the German participants of the "DesignerChar4Food" (D4F) project (CK: Project No. 2814ERA01A; NW-M: Project No. 2814ERA02A), the Spanish colleagues (JME and TFM) were funded by FACCE-CSA no 276610/MIT04-DESIGN-UPVASC and IT-932-16, MLC thanks the Spanish Ministry of Science, Innovation and Universities, project #RTI2018-099417-B-I00, cofinanced with EU FEDER funds and US colleagues (JN, JI and KS) were funded by The USDA-National Institute of Food and Agriculture (Project # 2014-35615-21971), USDA-ARS CHARnet and GRACENet programs - D4F greatly stimulated discussions. This work was also partially supported by the National Natural Science Foundation of China under a Grant number of 41501339, 21677119, 21277115, 41301551, 21407123, Jiangsu Province Science Foundation for Youths under a grant number of BK20140468, sponsored by Qing Lan Project

The soil nitrogen (N) availability and urease activity (UA) in a humid ecosystem with variable rainfall distribution and poor soil fertility are not well understood. A complete appreciation of N cycling in the soil&ndash, water&ndash, plant continuum is needed to better manage N and water in regions that will be strongly affected by climate change. A sorghum (Sorghum bicolor L.) study located in Florence, South Carolina, USA, was conducted using a variable-rate pivot system. We hypothesized that supplemental irrigation (SI) and N would enhance UA and N uptake while minimizing the concentration of N in porewater (TINW). The aim of the study was to assess the impact of SI (0, 50, and 100%) and N fertilization (0, 85, and 170 kg N ha&minus, 1) on: UA, total N (TNS), total inorganic N (TINS), TINW, and N uptake of sorghum. Results support our research hypothesis. The greatest UA was from 0% SI and 170 kg ha&minus, 1 (18.7 &micro, g N g&minus, 1 ha&minus, 1). Porewater N (mg L&minus, 1), when averaged across SI and N showed a significantly lower concentration at lower soil depth (9.9 &plusmn, 0.7) than the upper depth (26.1 &plusmn, 2.4). The 100% SI had the greatest biomass N uptake (NUPB) of 67.9 &plusmn, 31.1 kg ha&minus, 1 and grain N uptake (NUG) of 52.7 &plusmn, 20.5 kg ha&minus, 1. The greatest NUPB (70.9 &plusmn, 30.3 kg ha&minus, 1) and NUG (55.3 &plusmn, 16.5 kg ha&minus, 1) was from the application of 170 kg N ha&minus, 1. Overall, results showed that proper use of water and N enhanced soil N dynamics, and improved biomass productivity and N uptake of sorghum.

Grain sorghum is one of the top five cereal crops and an important grain crop throughout the world. It is generally considered more drought tolerant compared to other grain crops such as maize. Recently, in the U.S. eastern Coastal Plain region, there was an emphasis on increasing regional grain production in which grain sorghum played an important role. The region’s soils have low water holding capacities that combined with high rainfall variability cause crops frequently to be exposed to water stress. In this research, an experiment was conducted to evaluate the yield response of two grain sorghum varieties at different supplemental irrigation depths and three nitrogen levels. During our 3-year study, seasonal rainfall was adequate to produce acceptable grain sorghum yields. Seasonal rainfall ranged from 421, 365, and 357 mm in 2012, 2013, and 2014, respectively. These rainfall amounts were greater than the seasonal calculated crop evapotranspiration requirement, but rainfall distribution was not adequate to maintain acceptable soil water potentials throughout the growing season. Supplemental irrigation was 51, 38, and 13 mm in 2012, 2013, and 2014, respectively, to maintain soil water potential above -30 kPa. These irrigation amounts did not increase grain sorghum yields. No significant differences were found in grain yield between the two sorghum varieties or for increasing nitrogen applications. This lack of response to nitrogen applications may have been related to adequate supplies in the soil from previous crops. Results from this study suggest that there would be little benefit for supplemental irrigation for sorghum production in the U.S. eastern Coastal Plain. Keywords: Keyword. Grain sorghum, Irrigation, Irrigation management.

A 3-year (2013–2015) field study was conducted to evaluate the effect of integrated nutrient management (NM) and three irrigation scheduling methods (IS): irrigator pro (IPro); normalized difference vegetative index (NDVI) and soil water potentials (SWP) on phosphorus (P) dynamics and phosphatase activity in four Coastal Plains soil types (ST) at various growth stages (CS: V6, six leaves; V16, sixteen leaves; and R1, silking) of corn (Zea mays L.). Nitrogen fertilizer was applied at two rates: 157 and 224 kg ha−1 through the irrigation system in three applications. Phosphorus dynamics and phosphatase activity varied significantly (p ≤ 0.0001) with year (Y), CS and ST, but not with NM. Phosphorus uptake of corn had an increase of about 1200% from V6 to R1. Both the Mehlich extractable P and water soluble P showed declining trends from V6 to R1. Concentration of P in pore water differed significantly (p ≤ 0.05) with IS in 2014 and 2015, but not in 2013. The order of the concentrations of P in pore water (averaged across ST) as affected by IS is as follows: 2013 (IPro = NDVI = SWP); 2014 (SWP = IPro < NDVI); and 2015 (IPro < NDVI < SWP). Concentration of phosphatase among the different ST was affected by CS, from V6 to R1 and soil depth, but not with NM. The difference in phosphatase concentration between the upper and lower soil horizons (averaged across Y and ST) was about 67.7 μg g−1 h−1. Our results have significant implication on P mobility, availability and management in areas where inputs of P in fertilizers may have had exceeded P output in harvested crops. Our results further suggest that understanding of P inputs and outputs which include P accumulation in soils and plants, as well as P losses is critical to determining the environmental balance and accountability of P in agricultural ecosystem. It is imperative to have a holistic understanding of P dynamics from soil to plant by optimizing P management and improving P-use efficiency.

Agriculture is one of the largest sources of nutrient contamination, mainly inorganic nitrogen (N) fertilization of intensive crops, such as maize (Zea mays L). Proper irrigation management can reduce nutrient leaching while maintaining crop yield, which is critical in enhancing the sustainability of agricultural crops on soils with low water and nutrient holding capacities. A three-year (2012–2014) field study was conducted to evaluate the effects of three irrigation scheduling methods (ISM): Irrigator Pro (IPRO); Normalized Difference Vegetative Index (NDVI); and Soil Water Potentials (SWP) and two rates of N applications (NM) on pore water nitrate and phosphate in four soil types (ST) with maize production in Coastal Plain Region, USA. Soil pore water nitrate varied significantly with ISM and NM, but not with ST. The IPRO method had the lowest soil water pore nitrate followed by SWP and NDVI. The low N application rate resulted in lower nitrate concentration (13.4 mg L−1) than the high N rate (17.0 mg L−1). Soil water pore phosphate was not affected by ISM, NM and ST. The use of IPRO reduced the concentration of pore water nitrate by about 39% and 33% when compared with NDVI and SWP, respectively. Using IPRO method resulted in lower soil water pore nitrate and phosphate concentrations, results indicate scheduling method may be a way to reduce nutrient losses. Results of our study suggest that irrigation management decision may affect nitrogen and phosphorus availability for achieving optimum yield of maize while potentially minimizing nutrient losses via leaching.

Landfills have led to some of the most intense battles over pollution that has ever been seen. With the population skyrocketing worldwide, these landfills will only become more of a public issue as time goes on. Heavy metals from several sources especially in landfills are an increasingly urgent problem because of its contribution to environmental deterioration and intensive degradation of soil microbial biodiversity. Despite the arguments over landfills in general, few or no effort was undertaken to clean up contamination of heavy metals in abandoned landfills. In our study new methods were proposed using a green technology or phytoremediation with ferrous sulfate in enhancing cleanup of heavy metal polluted landfill soils. Composite soil samples were collected near an open abandoned dump site in Cabanatuan City, Nueva Ecija, Philippines. Three rates of sulfur: 0, 40 and 80 mmol kg -1 as ferrous sulfate (26% S) was thoroughly mixed with the soil. Four healthy seedlings of mustard (Brassica juncea, L) were transplanted to each pot. Soil pH showed a decreasing trend for soils treated with 0 and 80 mmol kg -1 of sulfur (S) after 15 days (8.12 to 7.38) and after 25 days (8.56 to 7.78). Application of ferrous sulfate significantly enhanced microbial activities in contaminated soils. Average respiration rate in soil with 0 mmol kg -1 S was about 2.0 mg kg -1 CO2-C compared with 19.0 mg kg -1 CO2-C for soils amended with 80 mmol S kg -1 . Although dry matter yield and uptake of heavy metals by mustard were somewhat variable with S application, solubility of copper (Cu), zinc (Zn) and manganese (Mn) in soils was significantly (p≤0.001) increased with S application. Our study has demonstrated the beneficial outcome of green technology in combination with ferrous sulfate in cleaning up heavy metals contamination in landfills and at the same time improving soil microbial biomass following phytoremediation.

There are mixed reports for biochars&rsquo, ability to increase corn grain and biomass yields. The objectives of this experiment were to conduct a three-year corn (Zea mays L.) grain and biomass production evaluation to determine soil fertility characteristics after designer biochars were applied to a highly weathered Ultisol. The amendments, which consisted of biochars and compost, were produced from 100% pine chips (PC), 100% poultry litter (PL), PC:PL 2:1 blend, PC mixed 2:1 with raw switchgrass (Panicum virgatum, rSG) compost, and 100% rSG compost. All treatments were applied at 30,000 kg/ha to a Goldsboro loam sandy (Fine-loamy, siliceous, sub-active, thermic Aquic Paleudult). Annual topsoil samples were collected in 5-cm depth increments (0 to 15-cm deep) and pH was measured along with Mehlich 1 phosphorus (M1 P) and potassium (M1 K) contents. After three years of corn production, there was no significant improvement in the annual mean corn grain or biomass yields. Biochar, which was applied from PL and PC:PL 2:1 blend, significantly increased M1 P and M1 K concentrations down to 10-cm deep, while the other biochar and compost treatments showed mixed results when the soil pH was modified. Our results demonstrated that designer biochar additions did not accompany higher corn grain and biomass productivity.

Mining activities could produce a large volume of spoils, waste rocks, and tailings, which are usually deposited at the surface and become a source of metal pollution. Phytostabilization of the mine spoils could limit the spread of these heavy metals. Phytostabilization can be enhanced by using soil amendments such as manure-based biochars capable of immobilizing metal(loid)s when combined with plant species that are tolerant of high levels of contaminants while simultaneously improving properties of mine soils. However, the use of manure-based biochars and other organic amendments for mine spoil remediation are still unclear. In this greenhouse study, we evaluated the interactive effect of biochar additions (BA) with or without the manure-based compost (MBC) on the shoots biomass (SBY), roots biomass (RBY), uptake, and bioconcentration factor (BCF) of Zn and Cd in corn (Zea mays L.) grown in mine soil. Biochar additions consisting of beef cattle manure (BCM), poultry litter (PL), and lodge pole pine (LPP) were applied at 0, 2.5, and 5.0% (w/w) in combination with different rates (0, 2.5, and 5.0%, w/w) of MBC, respectively. Shoots and roots uptake of Cd and Zn were significantly affected by BA, MBC, and the interaction of BA and MBC. Corn plants that received 2.5% PL and 2.5% BCM had the greatest Cd and Zn shoot uptake, respectively. Corn plants with 5% BCM had the greatest Cd and Zn root uptake. When averaged across BA, the greatest BCF for Cd in the shoot of 92.3 was from the application of BCM and the least BCF was from the application of PL (72.8). Our results suggest that the incorporation of biochar enhanced phytostabilization of Cd and Zn with concentrations of water-soluble Cd and Zn lowest in soils amended with manure-based biochars while improving the biomass productivity of corn. Overall, the phytostabilization technique and biochar additions have the potential to be combined in the remediation of heavy metals polluted soils.

Mining activities could produce a large volume of spoils, waste rocks, and tailings, which are usually deposited at the surface and become sources of metal pollution. Phytostabilization of the mine spoils could limit the spread of these heavy metals. Phytostabilization can be enhanced by using soil amendments like manure-based biochar capable of immobilizing metal(loid)s when combined with plant species that are tolerant of high levels of contaminants while simultaneously improving properties of mine soils. However, the use of manure-based biochar and other organic amendments for mine spoil remediation are still unclear. In this greenhouse study, we evaluated the interactive effect of biochar application and compost on shoots biomass yield (SBY), roots biomass yield (RBY), uptake, and bioconcentration factor (BCF) of Zn and Cd in corn (Zea mays L.) grown in mine soil. Biochar sources (BS) consisted of beef cattle manure (BCM); poultry litter (PL); and lodge pole pine (LPP) were applied at 0, 2.5, and 5.0% (w/w) in combination with different rates (0, 2.5, and 5.0%, w/w) of cattle manure compost (CMC), respectively. Shoots and roots uptake of Cd and Zn were significantly affected by BS, CMC, and the interaction of BS and CMC. Corn plants that received 2.5% PL and 2.5% BCM had the greatest Cd and Zn shoot uptake, respectively. Corn plants with 5% BCM had the greatest Cd and Zn root uptake. When averaged across BS, the greatest BCF for Cd in the shoot of 92.3 was from the application BCM and the least BCF was from the application of PL (72.8). Our results suggest that incorporation of biochar enhanced phytostabilization of Cd and Zn with concentrations of water-soluble Cd and Zn lowest in soils amended with both manure-based biochars while improving biomass productivity of corn. Overall, phytostabilization technique and biochar application have the potential to be combined in the remediation of heavy metals polluted soils.

Increasing environmental concerns about organic waste in paper mill effluents demand alternative wastewater management technology. We reported novel activation of fulvic acid-like in paper mill effluents using hydrogen peroxide (H

Variable-rate irrigation (VRI) systems are irrigation systems that are capable of applying different water depths both in the direction of travel and along the length of the irrigation system. However, when compared to traditional irrigation systems, VRI systems require a higher level of management. In this research, our objective was to evaluate and compare three irrigation management methods for their potential in managing VRI systems. The three irrigation management methods were the Irrigator Pro for Corn expert system, measured soil water potential (SWP), and remotely sensed crop vegetative indices (NDVI) to estimate crop coefficients. These irrigation treatments were implemented over six soil types under a VRI system for three years. Corn yields differed among years; average yields were 15.6 Mg ha -1 in 2012, 10.5 Mg ha -1 in 2013, and 13.5 Mg ha -1 in 2014. However, corn yields for the three irrigation treatments were not significantly different for any one year. The mean yearly irrigation applied in 2012, 2013, and 2014 was 57, 7, and 156 mm, respectively. The mean water use efficiency (WUE) over the three years was significantly different, with values of 29.8, 16.8, and 23.8 kg grain ha -1 mm -1 for 2012, 2013, and 2014, respectively. For each individual year, the WUE among irrigation treatments was not significantly different. For the six soils types, there were no significant differences for corn yield or WUE. The Irrigator Pro for Corn and NDVI treatments managed irrigations as well as the traditional SWP-based treatment under the VRI system from 2012 to 2014. Each of these irrigation treatments was able to adequately manage irrigation spatially and produce adequate crop yields for the region. Each of these irrigation management treatments could be used effectively to manage irrigations under a VRI system with different management zones.

Although an increase in soil fertility is the most frequently reported benefit linked to adding biochar to soils, there is still a need to pursue additional research that will improve our understanding on the impact of soil fertility enhancement because the effect could vary greatly between switchgrass (Panicum virgatum, L) residues (USG) and switchgrass biochars (SG). We hypothesized that SG with supplemental nitrogen (N) would deliver more positive effects on carbon (C) and N mineralization than USG. The objective of this study was to evaluate the effects of USG and SG, with or without supplemental inorganic N fertilizer on C and N mineralization in highly weathered Coastal Plain Ultisols. The application rate for SG and USG based on a corn yield goal of 112 kg ha(-1) was 40 Mg ha(-1). Inorganic N was added at the rate of 100 kg N ha(-1), also based on a corn yield of 7.03 tons ha(-1). Experimental treatments were: control (CONT) soil; control with N (CONT + N); switchgrass residues (USG); USG with N (USG + N); switchgrass biochars at 250 °C (250SG); SG at 250 °C with N (250SG + N); SG at 500 °C (500SG); and SG at 500 °C with N (500SG + N). Cumulative and net CO2-C evolution was increased by the additions of SG and USG especially when supplemented with N. Soils treated with 250SG (8.6 mg kg(-1)) had the least concentration of total inorganic nitrogen (TIN) while the greatest amount of TIN was observed from the CONT + N (19.0 mg kg(-1)). Our results suggest that application of SG in the short term may cause N immobilization resulting in the reduction of TIN.

Biochar may be a tool for mine spoil remediation; however, its mechanisms for achieving this goal remain unclear. In this study, Miscanthus (Miscanthus giganteus) biochar was evaluated for its ability to reclaim acidic mine spoils (pH < 3) through reducing metal availability, improving soil microbial enzymatic activity, and initial growth of grass seedlings. Biochar was applied at 0, 1, 2.5 and 5% (w/w) along with lime/no lime and fertilizer additions. Blue Wildrye (Elymus glaucus cv. ‘Elkton’) was planted and later the shoots and roots were collected and metal concentrations determined. Afterwards, each pot was leached with deionized water, and the leachate analyzed for pH, electrical conductivity (EC), dissolved organic carbon (DOC) and soluble metal concentrations. After drying, the spoil was extracted with 0.01 M CaCl(2) and Mehlich 3 (M3) to determine extractable Al, Cu, and Zn concentrations. Additionally, microbial activity was measured using a fluorescent β-glucosidase and N-acetyl-β-D-glucosaminidase assay. Spoil treated with lime and biochar had significantly greater pH and EC values. Significantly greater β-glucosidase activity occurred only in the 5% biochar plus lime treatment, while N-acetyl-β-D-glucosaminidase activities were not altered. Metal concentrations in rye shoot and roots were mixed. Lime additions significantly reduced extractable metal concentrations. Increasing biochar rates alone significantly reduced leachate DOC concentrations, and subsequently reduced leachable metal concentrations. Surprisingly, miscanthus biochar, by itself, was limited at mitigation, but when combined with lime, the combination was capable of further reducing extractable metal concentrations and improving β-glucosidase enzyme activity.

International audience; AbstractThe years of intensive tillage in Cambodia have caused significant decline in agriculture’s natural resources that could threaten its future of agricultural production and sustainability. Conventional tillage could cause rapid loss of soil organic matter, leading to a high potential for soil degradation and decline of environmental quality. Hence, a better and comprehensive process-based understanding of differential effects of tillage systems and crop management on crop yield is critically needed. A study was conducted in 10 farmer’s fields to evaluate the effect of conservation agriculture and conventional tillage on yield of selected crops and weeding activity in two villages of Siem Reap, Cambodia. The experiment was laid out following a 2 × 2 factorial treatment combination in randomized complete block design. Each treatment was replicated five times. Each farmer’s field was divided into four plots and was randomly assigned with production management and irrigation treatments, respectively. We demonstrated that our results supported the overall premises of conservation agriculture. Average yields of selected crops were significantly (≤ 0.001) improved in plots with conservation agriculture (17.1 ± 6.3 to 89.3 ± 40.2 Mg ha−1) compared with conventional tillage (18.8 ± 6.4 to 63.8 ± 27.7 Mg ha−1). Our results showed that manual weeding in all cropping seasons was significantly reduced by about 35% in conservation agriculture (169 ± 23 to 125 ± 18 man-day ha−1), which can be attributed to existing cover crops and surface mulch. Overall, our results suggest that in smallholder commercial household farms, adoption of conservation agriculture had a profitable production management system, which could save natural resources, improve yield, and reduce labor. We proved for the first time that in Cambodian smallholder commercial household farms, adoption of conservation agriculture saves natural resources, improves yield, and reduces labor. Additional studies are encouraged to further test the conservation agriculture system for a longer period of time, with repeated cropping sequences.

International audience; AbstractBiochar is the solid product that results from pyrolysis of organic materials. Its addition to highly weathered soils changes physico-chemical soil properties, improves soil functions and enhances crop yields. Highly weathered soils are typical of humid tropics where agricultural productivity is low and needs to be raised to reduce human hunger and poverty. However, impact of biochar research on scientists, politicians and end-users in poor tropical countries remains unknown; assessing needs and interests on biochar is essential to develop reliable knowledge transfer/translation mechanisms. The aim of this publication is to present results of a meta-analysis conducted to (1) survey global biochar research published between 2010 and 2014 to assess its relation to human development and environmental quality, and (2) deduce, based on the results of this analysis, priorities required to assess and promote the role of biochar in the development of adapted and sustainable agronomic methods. Our main findings reveal for the very first time that: (1) biochar research associated with less developed countries focused on biochar production technologies (26.5 ± 0.7%), then on biochars’ impact on chemical soil properties (18.7 ± 1.2%), and on plant productivity (17.1 ± 2.6%); (2) China dominated biochar research activities among the medium developed countries focusing on biochar production technologies (26.8 ± 0.5%) and on use of biochar as sorbent for organic and inorganic compounds (29.1 ± 0.4%); and (3) the majority of biochar research (69.0±2.9%) was associated with highly developed countries that are able to address a higher diversity of questions. Evidently, less developed countries are eager to improve soil fertility and agricultural productivity, which requires transfer and/or translation of biochar knowledge acquired in highly developed countries. Yet, improving local research capacities and encouraging synergies across scientific disciplines and countries are crucial to foster development of sustainable agronomy in less developed countries.

Although most soil properties were improved following application of crop residues and/or pyrolyzed crop residues, there is still a need to pursue additional research that will improve our understanding of the impact of soil fertility enhancement because the effect could vary greatly between uncharred sorghum (Sorghum bicolor L.) residues and pyrolyzed sorghum residues (SR). We hypothesized that sorghum biochars (SB) would deliver more significant impact on soil chemical changes than SR. The objective of this study was to evaluate the contrasting effects of SR and SB with or without supplemental inorganic P on soil chemical changes of Coastal Plains Ultisols with winter wheat. The application rates for SR and SB based on 13.5 Mg ha yield goal for wheat were 13,000 and 5,200 kg · ha, respectively. Inorganic P was added at the rate of 40 kg P · ha. Our results fully support our hypothesis that SB would deliver more positive effect on the changes of soil chemical properties than the SR. Most of the chemical properties of soils were significantly affected by sorghum treatments (SB + SR) and also varied widely between soil types. Overall, application of SB had small, but significant effects on soil pH, soil electrical conductivity, total carbon, and total nitrogen. Quite notably was the significant difference of these soil properties between soil types. Other aspects of soil chemical changes including extractable P, K, Ca, Mg, Al, and Fe were significantly affected by sorghum treatments. Our results have demonstrated widely differing and contrasting effects between SB and SR on changes in soil chemical properties of Coastal Plains Ultisols.

International audience; AbstractEthiopia faces high risk of soil carbon depletion for nearly half of its total land mass largely due to forest clearing and continuous cultivation. Conversion of natural ecosystems to cultivated agriculture resulted in losses of between 20 and 50% of the soil C stocks in the first meter of the soil depth. Dry Afromontane forests of northern Ethiopia have faced vast exploitation, and almost all these forests have been converted to agricultural lands affecting the functionality and stability of agroecosystem. Here, we studied the effect of land use-land cover changes on soil organic C, total N, and soil C sequestration. Specifically, (a) we characterized major soils of the Desa’a Dry Afromontane forest, northern Ethiopia, and (b) we analyzed the organic C and total N contents of soils with varying land use-land cover types of the Desa’a Dry Afromontane forest. Results show that soil organic C (1.9%) and total N (0.3%) were higher for the middle landscape position than that observed for the upper and lower landscape positions. Soil organic C that ranged from 1.2 in farmland to 2.3% in dense forest also varied with land use-land cover types. Concentration of soil organic C was different among dense forest (2.3%), open forest (1.7%), grazing land (1.6%), and farmland (1.2%). Due to the effect of land use-land cover types, soil total N varied from 0.2% in the farmland to 0.3% in the dense forest. The soil organic C and total nitrogen of the top and lower layer soils were 2.0 and 1.5 and 0.2 and 0.3%, respectively. The soil organic C sequestration for dense forest was significantly higher (48.5 t ha−1) than that of grassland, open forest, and farm land. The top soil sequestered higher soil organic C (44.9 t ha−1) than the lower soil layer. Thus, the top soil layers of dense forest at the middle landscape positions stored significant amount of soil organic carbon.

Increasing environmental concerns about organic waste in paper mill effluents demand alternative wastewater management technology. We reported novel activation of fulvic acid-like in paper mill effluents using hydrogen peroxide (H2O2) as oxidizer and titanium oxide (TiO2) as catalyst. Spectroscopic characteristics of fulvic acid-like in paper mill effluents before and after activation (PFA and PFA-Os, respectively) were compared with a benchmark fulvic acid extracted from leonardite (LFA). Results indicated that PFA-Os exhibited less lignin structures, more functional groups and lower molecular weight than PFA, sharing much similarity with LFA. Among PFA-Os with varying degrees of oxidation, PFA-O-3 activated with 1:2 vol ratio of paper mill effluent and 30% H2O2 for 20 min digestion at 90 °C stands out to be the optimal for further examination of its biological activity. Bioassays with rice seed/seedling indicated that applications of LFA at 2–5 mg-C/L and PFA-O-3 at 60–100 mg-C/L significantly increased rice seed germination rate and seedling growth under salt stress imposed with 100 mM NaCl. The mechanism was mainly through reduced oxidative damage via activation of antioxidative enzymes and lipid peroxidation. This study provides the needed technical basis of safer and cleaner technologies for innovative management of paper mill effluents.

Low-phosphorus (P) litter, a manure treatment byproduct, can be used as an organic soil amendment and nitrogen (N) source but its effect on N mineralization is unknown. A laboratory incubation study was conducted to compare the effect of adding untreated (fine or pelletized) broiler litter (FUL or PUL) versus extracted, low-P treated (fine or pelletized) broiler litter (FLP or PLP) on N dynamics in a sandy soil. All four litter materials were surface applied at 157 kg N ha&minus, 1. The soil accumulation of ammonium (NH4+) and nitrate (NO3&minus, ) were used to estimate available mineralized N. The evolution of carbon dioxide (CO2), ammonia (NH3), and nitrous oxide (N2O) was used to evaluate gaseous losses during soil incubation. Untreated litter materials provided high levels of mineralized N, 71% of the total N applied for FUL and 64% for PUL, while NH3 losses were 24% to 35% and N2O losses were 3.3% to 7.4% of the total applied N, respectively. Soil application of low-P treated litter provided lower levels of mineralized N, 42% for FLP and 29% for PLP of the total applied N with NH3 losses of 5.7% for FLP for and 4.1% for PLP, and very low N2O losses (0.5%). Differences in mineralized N between untreated and treated broiler litter materials were attributed to contrasting C:N ratios and acidity of the low-P litter byproducts. Soil application of treated low-P litter appears as an option for slow mineral N release and abatement of NH3 and N2O soil losses.

Forage-based cow-calf operations may have detrimental impacts on the chemical status of groundwater and streams and consequently on the ecological and environmental status of surrounding ecosystems. Assessing and controlling phosphorus (P) inputs are, thus, considered the key to reducing eutrophication and managing ecological integrity. In this paper, we monitored and evaluated P concentrations of groundwater (GW) compared to the concentration of surface water (SW) P in forage-based landscape with managed cow-calf operations for 3 years (2007-2009). Groundwater samples were collected from three landscape locations along the slope gradient (GW1 10-30% slope, GW2 5-10% slope, and GW3 0-5% slope). Surface water samples were collected from the seepage area (SW 0% slope) located at the bottom of the landscape. Of the total P collected (averaged across year) in the landscape, 62.64% was observed from the seepage area or SW compared with 37.36% from GW (GW1 = 8.01%; GW2 = 10.92%; GW3 = 18.43%). Phosphorus in GW ranged from 0.02 to 0.20 mg L(-1) while P concentration in SW ranged from 0.25 to 0.71 mg L(-1). The 3-year average of P in GW of 0.09 mg L(-1) was lower than the recommended goal or the Florida's numeric nutrients standards (NNS) of 0.12 mg P L(-1). The 3-year average of P concentration in SW of 0.45 mg L(-1) was about fourfold higher than the Florida's NNS value. Results suggest that cow-calf operation in pasture-based landscape would contribute more P to SW than in the GW. The risk of GW contamination by P from animal agriculture production system is limited, while the solid forms of P subject to loss via soil erosion could be the major water quality risk from P.

Grazing can accelerate and alter the timing of nutrient transfer, and could increase the amount of extractable phosphorus (P) cycle from soils to plants. The effects of grazing management and/or forage type that control P cycling and distribution in pasture's resources have not been sufficiently evaluated. Our ability to estimate the levels and changes of soil-extractable P and other crop nutrients in subtropical beef cattle pastures has the potential to improve our understanding of P dynamics and nutrient cycling at the landscape level. To date, very little attention has been paid to evaluating transfers of extractable P in pasture with varying grazing management and different forage type. Whether or not P losses from grazed pastures are significantly greater than background losses and how these losses are affected by soil, forage management, or stocking density are not well understood. The objective of this study was to evaluate the effect of grazing management (rotational versus "zero" grazing) and forage types (FT; bahiagrass, Paspalum notatum, Flugge versus rhizoma peanuts, Arachis glabrata, Benth) on the levels of extractable soil P and degree of P saturation in beef cattle pastures. This study (2004-2007) was conducted at the Subtropical Agricultural Research Station, US Department of Agriculture-Agricultural Research Service located 7 miles north of Brooksville, FL. Soil (Candler fine sand) at this location was described as well-drained hyperthermic uncoated Typic Quartzipsamments. A split plot arrangement in a completely randomized block design was used and each treatment was replicated four times. The main plot was represented by grazing management (grazing vs. no grazing) while forage types (bahiagrass vs. perennial peanut) as the sub-plot treatment. Eight steel exclosures (10 × 10 m) were used in the study. Four exclosures were placed and established in four pastures with bahiagrass and four exclosures were established in four pastures with rhizoma peanuts to represent the "zero" grazing treatment. The levels of soil-extractable P and degree of P saturation (averaged across FT and soil depth) of 22.1 mg kg(-1) and 11.6 % in pastures with zero grazing were not significantly (p ≤ 0.05) different from the levels of soil-extractable P and degree of P saturation of 22.8 mg kg(-1) and 12.9 % in pastures with rotational grazing, respectively. On the effect of FT, levels of soil-extractable P and degree of P saturation were significantly higher in pastures with rhizoma peanuts than in pastures with bahiagrass. There was no net gain of soil-extractable P due to the presence of animals in pastures with rotational grazing. Averaged across years, soil-extractable P in pastures with rotational grazing and with "zero" grazing was less than 150 mg kg(-1), the water quality protection. There had been no movement of soil-extractable P into the soil pedon since average degree of P saturation in the upper 15 cm was 14.3 % while the average degree of P saturation in soils at 15-30 cm was about 9.9 %. Overall, average extractable P did not exceed the crop requirement threshold of 50 mg P kg(-1) and the soil P saturation threshold of 25 %, suggesting that reactive P is not a problem. Our study revealed that rhizoma peanuts and bahiagrass differ both in their capacity to acquire nutrients from the soil and in the amount of nutrients they need per unit growth. Rhizoma peanuts, which are leguminous forage, would require higher amounts of P compared with bahiagrass. The difference in the amount of P needed by these forages could have a profound effect on their P uptake that can be translated to the remaining amount of P in the soils. Periodic applications of additional P may be necessary especially for pastures with rhizoma peanuts to sustain their agronomic needs and to potentially offset the export of P due to animal production. Addition of organic amendments could represent an important strategy to protect pasture lands from excessive soil resources exploitation.

Coal-fuelled power plants can discharge hazardous materials, particularly heavy metals such as lead (Pb). An alternative way of reducing Pb concentration from contaminated sediments is through phytoremediation. Presently, there are few research findings on the phytoremediation potential of mangroves on metals like Pb. The study was conducted to survey and identify mangroves that thrive near the coal-fired power plant and to assess the phytoremediation potential of mangroves on Pb in sediment. The study sites were located in the mangrove ecosystems of Sitio Oyon and Sitio Asinan in Masinloc, Zambales, Philippines. The first stage of our study was to survey and identify the mangrove species. The second stage was to assess the levels of Pb in the sediments, water, and tissues of mangrove trees. The diversity assessment of the mangrove species was done through the use of 10 × 12 m quadrat technique. Water and sediment samples from each mangrove ecosystem were collected using composite sampling methods. Three mangrove species were identified in the study sites: Avicennia marina, Rhizophora stylosa, and Sonneratia alba. The order of importance of the mangrove trees in the two sampling locations, based on an importance value index (IVI), were as follows: SA (IVI = 171.20) > AM (77.79) > RS (51.01). The total uptake of Pb from sediments near the power plants varied significantly (p ≤ 0.001) among the three mangrove species. S. alba had the highest Pb uptake of 48.4 kg ha−1 followed by A. marina (23.1 kg ha−1), and R. stylosa (2.4 kg ha−1). These three mangrove species have the potential to phytoremediate Pb in the sediment. The three mangrove species present in the coastal ecosystem near the electric power plant—A. marina, R. stylosa, and S. alba—were potential phytoremediators of sediment Pb. The present study indicated that the mangroves possess beneficial characteristics that remove Pb from contaminated sediments in areas directly affected by coal-fired power plants, and thus have potential phytoremediation properties.

The cow-calf (Bos taurus) industry in subtropical United States and other parts of the world that depends almost totally on grazed pastures is facing several production constraints like changing climatic conditions and increasing cost of fertilizers, especially nitrogen (N). Particularly little is known about the response of forage species to the combined effect of water-logging and the addition of N. A two-year greenhouse study was conducted in 2008 and 2009 to determine i) the effect of flooding duration on N recovery and agronomic efficiency of bahiagrass (Paspalum notatum Fluegge) compared with two flooding tolerant forages, limpograss (Hemarthria altissima Poir), and maidencane (Panicum hematomon Schult) and ii) if N fertilization could mitigate the negative effect of flooding. Nitrogen recovery and agronomic efficiency varied significantly (P ≤ 0.001) among forage species. Averaged across levels of N, N recovery of bahiagrass and limpograss was reduced by about 41% and 56%, respectively after 84 d of continued flooding while N recovery of maidencane was slightly increase by about 5% between 0 and 84 d of flooding. Agronomic efficiencies of bahiagrass (41% to 26%) and limpograss (44% to 31%) were reduced by flooding while agronomic efficiency of maidencane was increased from 24% (no flooding) to 46% at 84 d of continued flooding. However, N recovery and agronomic efficiency of three forage species was positively affected by N fertilization. The overall N recovery of bahiagrass, limpograss, and maidencane ranged from 44% to 59%. Nitrogen fertilization could improve N recovery and agronomic efficiency of forage species under waterlogged condition.

Land, surface waters, and ground water worldwide, are increasingly affected by contaminations from industrial, research experiments, military, and agricultural activities either due to ignorance, lack of vision, carelessness, or high cost of waste disposal and treatment. The rapid build-up of toxic pollutants (metals, radionuclide, and organic contaminants in soil, surface water, and ground water) not only affects natural resources, but also causes major strains on ecosystems. Interest in phytoremediation as a method to solve environmental contamination has been growing rapidly in recent years. This green technology that involved “tolerant plants” has been utilized to clean up soil and ground water from heavy metals and other toxic organic compounds. Phytoremediation involves growing plants in a contaminated matrix to remove environmental contaminants by facilitating sequestration and/or degradation (detoxification) of the pollutants. Plants are unique organisms equipped with remarkable metabolic and absorption capabilities, as well as transport systems that can take up nutrients or contaminants selectively from the growth matrix, soil or water. As extensive as these benefits are, the costs of using plants along with other concerns like climatic restrictions that may limit growing of plants and slow speed in comparison with conventional methods (i.e., physical and chemical treatment) for bioremediation must be considered carefully. While the benefits of using phytoremediation to restore balance to a stressed environment seem to far outweigh the cost, the largest barrier to the advancement of phytoremediation could be the public opposition. The long-term implication of green plant technology in removing or sequestering environmental contaminations must be addressed thoroughly. As with all new technology, it is important to proceed with caution.

O Brasil é um dos maiores produtores de alimentos do mundo. As produções agrícolas e animais estão concentradas em determinadas regiões do país. A pecuária tem sido percebida como uma ameaça constante para a quantidade e a qualidade dos recursos hídricos. O objetivo deste estudo foi avaliar o impacto de sistemas de produção pecuários/agrícolas na qualidade da água superficial na sub-bacia do Rio Pinhal que está localizado em Concórdia, Santa Catarina. Oito pontos de amostragem, representando diferentes usos da terra (LU1: gado leiteiro; LU2: sem animais; LU3: gado leiteiro + porcos + aves de corte + culturas; LU4: porcos + aves de corte + culturas; LU5: gado leiteiro + porcos + aves de corte + culturas + humanos; LU6: gado leiteiro + porcos + culturas; LU7 e LU8: gado leiteiro + porcos) foram avaliados. As águas foram amostradas durante o verão, outono, primavera e inverno de 2006 a 2009. LU1 apresentou a pior qualidade da água com altas concentrações de sólidos suspensos totais (SST) e demanda química de oxigênio. Neste ponto, os animais tinham acesso ao rio. A maior concentração de nitrato (NO3-N) foi encontrada na foz do rio. Houve maiores concentrações de SST, NO3-N e NO2-N na estação chuvosa. Nesta estação há intensiva aplicação de fertilizantes orgânicos para os campos de milho. Outono e inverno apresen-taram a pior qualidade da água em relação à concentração de nitrogênio. Os resultados mostraram forte relação entre as fontes de poluição e qualidade da água. O gerenciando o uso de fertilizantes orgânicos com o de fertilizantes químicos e a recuperação das áreas ripárias são ações mitigatórias importantes para proteger a qualidade da água do rio Pinhal.