Effects of vegetation removal on native soil quality in eastern Arkansas

Aboveground vegetation removal practices, such as cutting and baling and burning, can both positively and negatively affect a prairie ecosystem. Burning can stimulate growth and species diversity, but removing vegetation and the nutrients it contains without equal replenishment of those nutrients could cause a steady decline in available soil nutrients. The objective of this study was to evaluate the effects of vegetation removal techniques in a native tallgrass prairie in eastcentral Arkansas. Soil samples were collected from the top 10 cm in each soil mapping unit that existed in each of three prairie areas that differed by the amount of time since aboveground vegetation had been removed by cutting and baling (i.e., 0, 6, and 24 years). Soil samples were analyzed for bulk density, particle-size distribution, organic matter, pH, electrical conductivity (EC), and extractable nutrients. Bulk density and EC were highest in the prairie area in which vegetation removal by cutting and baling still occurs at the present, but organic matter was highest in the prairie area in which cutting and baling ceased in 1998 (i.e., 6 years prior). Soil pH was highest in the prairie area in which cutting and baling ceased in 1980 (i.e., 24 years prior). No consistent trends among the three prairie treatments existed for extractable soil nutrients. The results of this study indicate that common prairie management practices in the Grand Prairie region of east-central Arkansas significantly affect soil physical and chemical properties. Prairie management practices need to be considered carefully to insure long-term sustainability and proper ecosystem functionin

Rice Biomass Response to Various Phosphorus Fertilizers in a Phosphorus-Deficient Soil Under Simulated Furrow-Irrigation

Wastewater-recovered phosphorus (P), in the form of the mineral struvite (MgNH4PO4∙6H2O), may provide a sustainable alternative to decreasing rock-phosphate reserves. Struvite can be generated via precipitation methods, potentially reducing the amount of P runoff to aquatic ecosystems. The objective of this greenhouse tub study was to evaluate the effects of chemically and electrochemically precipitated struvite (CPST and ECST, respectively) on aboveground plant response in a hybrid rice cultivar grown using furrow-irrigation compared to other common fertilizer-P sources [i.e., triple super phosphate (TSP) and diammonium phosphate (DAP)] using three replications of fertilizer treatment in a P-deficient silt loam (Typic Glossaqualfs). Aboveground rice dry matter (DM), aboveground DM P uptake, grain yield, and grain P uptake from CPST and ECST did not differ from DAP or TSP. However, aboveground DM P concentration was numerically largest (P \u3c 0.05) from TSP (0.05 %), which did not differ from DAP, and was at least 2.5 times larger than that from ECST, CPST, and the unamended control (UC). Similar rice responses among struvite and other common fertilizer-P sources suggest CPST and ECST are both possible alternative fertilizer-P sources that warrant further research into struvite’s role in food production and water quality restoration and preservation

Bermudagrass growth in soil contaminated with hydraulic fracturing drilling fluid

Hydraulic fracturing is the process of injecting aqueous solutions at high pressure to break apart rock formations and increase the extraction of natural gas. The solutions are recovered and have been land-applied as one disposal technique. Excessive fluid application can result in increased soil salinity that can inhibit plant growth. The objective of this greenhouse study was to evaluate the effects of inorganic fertilizer, broiler litter, and Milorganite® and soil depth interval (0-15 cm or 0-30 cm) on the growth of bermudagrass [Cynodon dactylon (L.) Pers] in soil that was collected from a site that had been contaminated with fracturing fluid and was initially devoid of vegetation. Amendment rates were added to provide 60 mg of plant-available N/kg. Bermudagrass was sprigged and harvested after nine weeks and shoot, root, and total biomass were determined. Addition of inorganic fertilizer, broiler litter, or Milorganite® resulted in greater shoot biomass compared to unamended soil. Plants grown in 0-30-cm-depth soil had greater root biomass compared to the 0-15-cm soil depth. The addition of recommended plant nutrients and mixing of the contaminated surface soil with the subsurface soil enhanced bermudagrass growt

Corn response to wastewater-recycled phosphorus fertilizers

The ability to recycle phosphorus (P) from wastewaters could provide a sustainable, continuous source of P that might also help protect surface water quality from P enrichment. The mineral struvite (MgNH4PO4 · 6H2O) is an understudied material that can be created from P- and nitrogen (N)-containing wastewater and has been shown to have agricultural fertilizer value. The objective of this study was to evaluate the effects of electrochemically precipitated struvite (ECST), chemically precipitated struvite (Crystal Green; CG), diammonium phosphate (DAP), monoammonium phosphate (MAP), rock phosphate (RP), and triple superphosphate (TSP) on corn (Zea mays) response in a greenhouse pot study. The effects of fertilizer treatment on select plant properties were evaluated. Corn plant properties and elemental tissue concentrations differed (P \u3c 0.05) among fertilizer amendments. Belowground dry matter from ECST was 1.9 times greater than that from CG, TSP, DAP, and the No P/+N, and No P/-N control treatments. Corn cob-plus-husk tissue P concentration from ECST was similar to that from MAP and DAP and was 1.2 times larger than that from CG. Corn stem-plus-leaves tissue P concentration from ECST differed from that from all other treatments and was 1.8 times greater than that from the No P/+N control. Results generated from this study not only provide information on the new, thus understudied, electrochemically precipitated struvite material, but also further demonstrate why more research should be conducted on the implementation of struvite as an alternative fertilizer-P source and struvite’s potential impact on sustainable food production and the preservation of water resources

Landuse and Physiographic Region Effects on Soil Carbon and Nitrogen Sequestration in Arkansas

Increasing understanding of soil carbon (C) sequestration dynamics and general functioning in disappearing native grassland ecosystems, has the potential to enhance soil rehabilitation and ecosystem restoration. The objective of this study was to evaluate the effects of landuse (native tallgrass prairie and managed agriculture) and physiographic region (northwest Arkansas and east-central Arkansas) on the change in soil C and nitrogen (N) storage and other soil properties over a 15-year period. Despite the native prairie losing soil C at a rate of 4.7 Mg ha−1 year−1 over the 15-year duration of this study, soil C storage in 2016 was more than 2.5 times greater in the native prairie than in the cultivated agroecosystems in the Grand Prairie. Averaged across landuse, TC concentration (P < 0.01) and content (P < 0.01) changed more over time in the Ozark Highlands region of northwest Arkansas (0.02% year−1 and 0.28 Mg ha−1 year−1, respectively), than in the Grand Prairie region of east-central Arkansas. This study demonstrates the value of direct measurements over time for assessing temporal changes in soil properties and results can potentially direct future restoration activities to be as successful as possible

Rice Biomass Response to Various Phosphorus Fertilizers in a Phosphorus-Deficient Soil Under Simulated Furrow-Irrigation

Wastewater-recovered phosphorus (P), in the form of the mineral struvite (MgNH4PO4∙6H2O), may provide a sustainable alternative to decreasing rock-phosphate reserves. Struvite can be generated via precipitation methods, potentially reducing the amount of P runoff to aquatic ecosystems. The objective of this greenhouse tub study was to evaluate the effects of chemically and electrochemically precipitated struvite (CPST and ECST, respectively) on aboveground plant response in a hybrid rice cultivar grown using furrow-irrigation compared to other common fertilizer-P sources [i.e., triple super phosphate (TSP) and diammonium phosphate (DAP)] using three replications of fertilizer treatment in a P-deficient silt loam (Typic Glossaqualfs). Aboveground rice dry matter (DM), aboveground DM P uptake, grain yield, and grain P uptake from CPST and ECST did not differ from DAP or TSP. However, aboveground DM P concentration was numerically largest (P \u3c 0.05) from TSP (0.05 %), which did not differ from DAP, and was at least 2.5 times larger than that from ECST, CPST, and the unamended control (UC). Similar rice responses among struvite and other common fertilizer-P sources suggest CPST and ECST are both possible alternative fertilizer-P sources that warrant further research into struvite’s role in food production and water quality restoration and preservation

Long-Term Changes in Soil Surface Properties as Affected by Management Practices in a Wheat-Soybean, Double-Crop System

Long-term agricultural sustainability and productivity are controlled by the integrative effects of different management practices on the soil. Many Arkansas producers use the double-crop system to grow soybeans [Glycine max (L.) Merr] and wheat (Triticum aestivum L.). The objective of this study was to evaluate the effects of agricultural management practices, including residue level, tillage, irrigation, burning, and soil depth on the change in various soil properties from 2010 to 2020 in a long-term, wheat-soybean, double-crop system on a silt-loam soil (Glossaquic Fraglossudalfs) in eastern Arkansas. Soil nutrients tended to accumulate over time, the most in the top 10 cm, while soil nutrient contents in the 10- to 20-cm depth interval tended to not significantly change over time. Soil bulk density (BD) generally decreased across all treatments over time. Soil organic matter (SOM) content increased under all treatment combinations by 0.097 kg/ha. Soil BD decreased and SOM numerically increased the most in the no-till/no-burn treatment at the top 10 cm of the soil. Total carbon was 9.2 times greater, while total nitrogen was 48 times greater in the top 10 cm of the soil than the 10- to 20-cm depth. Soil pH was 1.9 times greater under irrigation than under non-irrigated treatments. Quantifying soil-property change over time will help producers to better understand the long-term effects of various residue and water management practices and to find reasonable, more sustainable alternative practices

Methane Emissions from Rice Production in the United States — A Review of Controlling Factors and Summary of Research

Flooded rice (Oryza sativa L.) cultivation has been identified as one of the leading global agricultural sources of anthropogenic methane (CH4) emissions. Furthermore, it has been estimated that global rice production is responsible for 11% of total anthropogenic CH4 emissions. Considering that CH4 has a global warming potential that is approximately 25 times more potent, on a mass basis, than carbon dioxide (CO2) and rice production is globally extensive and concentrated in several mid-southern and southern states and California, the purpose of this review is two-fold: (i) discuss the factors known to control CH4 production in the soil and transport to the atmosphere from rice cultivation and (ii) summarize the historic and recent research conducted on CH4 emissions from rice production in the temperate United States. Though some knowledge has been gained, there is much more that still needs to be learned and understood regarding CH4 emissions from rice production in the United States, its contribution to climate change, and potential mitigation strategies. Extending the current knowledge base surrounding CH4 emissions from rice cultivation will help regulatory bodies, such as the Environmental Protection Agency, refine greenhouse gas emissions factors to combat the potential negative effects of climate change

Soil Moisture Regime and Mound Position Effects on Soil Water and Vegetation in a Native Tallgrass Prairie in the Mid-Southern United States of America

Prairie mounds are unique soil surface features that will become increasingly scarce as native tallgrass prairies are continually lost. This study aimed to evaluate (i) whether the soil moisture regime (SMR), mound position, and soil depth affect soil volumetric water content (VWC) and (ii) whether the SMR and mound position affect vegetation over time. Soil VWC was measured continuously from April 2017 to June 2018, and vegetation was sampled in June and August 2017 and in May and August 2018. Maximum VWC for selected rainfall events was ~ 2.5 times greater at 10 cm in the aquic inter-mound than the udic mound position at 30 cm. Soil dry-down rates were four times greater in the udic soil at 10 cm than the aquic soil at 30 cm. Aboveground plant biomass was numerically largest (8489 kg ha−1) at the aquic summit in August 2018 and smallest (1280 kg ha−1) at the aquic inter-mound in May 2018. Results clearly demonstrate the effects that prairie mound topography and differing SMRs have on soil water dynamics and prairie vegetation and suggest that management efforts need to account for mound topography and SMR in order to be most successful

Infiltration and short-term movement of nitrogen in a silt-loam soil typical of rice cultivation in Arkansas

Rice production in Arkansas is one of the top three crop commodities in terms of cash receipts. Researchers and farmers report that nitrogen (N) needs to be managed according to a variety of factors with two important ones being soil and fertilizer type. The objectives of this experiment were to determine: 1) the degree to which floodwater-incorporated N applied as urea or as ammonium sulfate infiltrates intact cores (7.2-cm dia., 10-cm depth) containing DeWitt siltloam soil, and 2) the distribution of N during 12 h of ponding. Inorganic-N concentrations were analyzed at 2-cm depth intervals in cores following removal of the flood. Nitrogen from applied fertilizer was recovered as ammonium. Ammonium sulfate-N remained in the top 4 cm of soil with concentrations of 375 µg N g-1 in the surface 2 cm and 300 µg N g-1 at the 2 - 4 cm depth after 12 hr of ponding. At all depth intervals below 4 cm, ammonium sulfate-N remained below 30 µg N g-1. In contrast, after 12 h of ponding, N in soil receiving urea was 105 µg N g-1 in the top 2 cm and 173 µg N g-1 at 2-4 cm. At 4-6, 6-8, and 8-10 cm, N was 109, 108, and 35 µg N g-1, respectively, after 12 h of ponding. These results demonstrate immediate and deeper movement of ammonium into silt loam soil receiving urea as compared to ammonium sulfate, demonstrating how the form of N in fertilizer affects its movement into the soil profile