Soil- And Water-Based Management Strategies for Revegetation and Productivity Improvement of Brackish Marsh Soil.

Laboratory, greenhouse, and field experiments were conducted on brackish marsh soil of Hackberry, Louisiana (LA). This study was aimed to obtain detailed information on some soil- and water-based management factors that were applicable to the revegetation and productivity improvement of the area. This area was inundated by brackish-saline water, and is now open water, almost totally void of vegetation. The deteriorating productivity and continuous loss of vegetation in the study area can be related to the seasonal and temporal biochemical transformations. These transformations were significantly correlated to precipitation and minimum and maximum temperature in the area. Stochastic regression models were established to describe seasonal and temporal behavior of water and soil pH, electrical conductivity, total dissolved solids, and ionic strength in brackish marsh. The variability of individual soil properties in the study area as indicated by the coefficient of variations differed significantly (p = 0.01). A uniform application of any soil amendments like fertilizer or gypsum in the area that possessed spatially variable soil would result in over application in some parts of the area and under application in others. Soil drying significantly reduced urease activity in the area and was detrimental to the overall growth and yield of marsh vegetation. There was zero survival in the non-flooded plots except that marsh hay cordgrass had survival rate of 32.8%. The four species of marsh vegetation: Spartina patens Muhl. (marsh hay cordgrass), Distichlis spicata L. (salt grass), Paspalum vaginatum SW. (joint grass), and Scirpus americanus Pers. (freshwater three-square) responded significantly to N and gypsum (G) applications. Their overall yield response was described as DMY = 2.68 + 1.62N $-$ 0.98N\sp2 + 0.37N\sp3 $-$ 0.73G + 0.62G\sp2. Plots receiving 7 Mg gypsum ha\sp{-1} produced significantly more dry matter yield (DMY) than did the control. This treatment increased the DMY of joint grass (5.04 to 8.08 Mg ha\sp{-1}), marsh hay cordgrass (1.90 to 6.91 Mg ha\sp{-1}, salt grass (0.97 to 2.79 mg ha\sp{-1}), and three-square (1.55 to 2.84 Mg ha\sp{-1}) in flooded plots. Significantly higher survival rates of plants were observed in flooded plots treated with gypsum than in the plots without gypsum or flooding

Biochar research activities and their relation to development and environmental quality. A meta-analysis

Biochar 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. © 2017, The Author(s)

Sustainable cow-calf operations and water quality: A review

As animal agriculture has evolved to larger production operations in subtropical regions of United States, the problems associated with manure handling, storage and disposal have grown significantly. Understanding the interaction effects of sustainable cow farming with water-table management, nutrient dynamics and water quality in pastures could be the key to reducing nutrients in runoff. Soils do not contribute equally to nutrient export from watersheds or have the same potential to transport nutrient to runoff nor would soil test levels accurately predict total dissolved nutrients. Better understanding of soil nutrient dynamics and crop nutrient changes resulting from different management systems should allow us to predict potential impact on adjacent surface waters. In many states, these issues are critical and of increasing importance among environmentalists, ranchers, and public officials particularly in the case of N and P. One of the first steps in assessing N or P level on any farm is to consider total N or total P inputs and outputs. In Florida, reduction of P transport to receiving water bodies is the primary focus of several studies because P has been found to be the limiting nutrient for eutrophication in many aquatic systems. Long-term monitoring of the changes in soil nutrients, especially soil P would enable us to predict soil chemical or physical deterioration under continuous forage-livestock cultivation and to adopt measures to correct them before they actually happen. Despite substantial measurements using both laboratory and field techniques, little is known about the spatial and temporal variability of nutrient dynamics across the entire landscape, especially in agricultural landscapes with cow-calf operations

Efficacy of Supplemental Irrigation and Nitrogen Management on Enhancing Nitrogen Availability and Urease Activity in Soils with Sorghum Production

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–water–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−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−1 (18.7 µg N g−1 ha−1). Porewater N (mg L−1), when averaged across SI and N showed a significantly lower concentration at lower soil depth (9.9 ± 0.7) than the upper depth (26.1 ± 2.4). The 100% SI had the greatest biomass N uptake (NUPB) of 67.9 ± 31.1 kg ha−1 and grain N uptake (NUG) of 52.7 ± 20.5 kg ha−1. The greatest NUPB (70.9 ± 30.3 kg ha−1) and NUG (55.3 ± 16.5 kg ha−1) was from the application of 170 kg N ha−1. Overall, results showed that proper use of water and N enhanced soil N dynamics, and improved biomass productivity and N uptake of sorghum

Recycling biosolids and lake-dredged materials to pasture-based animal agriculture: alternative nutrient sources for forage productivity and sustainability. A review

Domestic sewage sludge or biosolids and lake-dredged materials are examples of materials that can be used to cut fertilizer costs in pasture-based animal agriculture. Sustainable biosolids and lake-dredged materials management is based upon controlling and influencing the quantity, quality and characteristics of these materials in such a way that negative impacts to the environment are avoided and beneficial uses are optimized. This article examines the following two key questions. Is the use of these materials in an agricultural setting harmless and sensible? Is the use of biosolids secure in all climates, in all soils and is it sustainable over the long term? Recycling biosolids and lake-dredged materials to pasture-based animal production is quite productive as alternative nutrient sources for forage production. Perennial grass can be a good choice for repeated applications of biosolids and lake-dredged materials. Although biosolids and lake-dredged materials supply some essential plant nutrients and provide soil property-enhancing organic matter, land-application programs still generate some concerns because of possible health and environmental risks involved. Repeated applications of biosolids and lake-dredged materials indicate no harmful effects on soil quality and forage quality. Beneficial uses of biosolids and lake-dredged materials are both economical and environmental. The concentrations of soil nitrogen and phosphorus following repeated application of biosolids were far below the contamination risk in the environment. The residual effect of biosolids over the long term can be especially significant in many forage-based pastures where only 50% of the million hectares of pastures are given inorganic nitrogen yearly. Long-term studies have demonstrated the favorable and beneficial effects of added lake-dredged materials on the early establishment of bahiagrass in sandy pasture fields. Often these materials can be obtained at little or no cost to the farmers or landowners. Lake-dredged materials can be used as soil amendments (lime and fertilizer) for early establishment of bahiagrass in beef cattle pastures. Bahiagrass in plots that were treated with biosolids and lake-dredge materials had significantly higher forage yield and crude protein content when compared with those bahiagrass in the control plots or untreated plants

Levels and Changes of Soil Phosphorus in Subtropical Beef Cattle Pastures

Long-term pasture management is believed to change soil chemical properties, but little is known about whether pasture management, such as fertilizer application, grazing, or haying can initiate such change in sandy and well-drained subtropical beef pastures. The objective of this study was to investigate the long term effect of pasture management (grazing+haying, GZ+HY) on soil phosphorus (P) dynamics (levels and changes) in subtropical beef cattle pastures with bahiagrass (BG, Paspalum notatum) and rhizoma peanut (RP, Arachis glabrata) with (WP) or without (WNP) P fertilization in Brooksville, FL from 1988 to 2000. Soil P dynamics in Subtropical Agricultural Research Station (STARS) was significantly affected by P fertilization (p ≤ 0.001) and pasture management ( p ≤ 0.0001). The soil P levels across years from the fertilized fields of 119.0 ± 4.9mg kg-1 was significantly higher than those pasture fields with no P fertilization (62.8 ± 7.8mg kg-1). However, during the past 12 years, there was no P build up despite of the annual application of P-containing fertilizers in addition to the daily in-field loading of animal waste bi-products like fecals and urine. The average soil test values for P in STARS had declined by about 28.3%. The soil test values of P in BG-GZ was about 23% higher than that of BG-GZ+HY, suggesting that GZ followed by HY could have lowered levels of soil P. Soil testing program in the station should continue to measure the amount of soil P that is proportional to what is available to BG and RP, and also continue looking at alternative soil P tests that are better predictors of the loss and/or build up of total and dissolved P to soil and water systems

Long-term effect of cow congregation zone on soil penetrometer resistance: implications for soils and forage quality

Higher degree of soil penetrometer resistance can reduce forage yields and can lead to water and soil quality degradation due to increased runoff and soil structure destruction. The inability of roots to penetrate in soils with high penetrometer resistance will result in decreased yield. With less root penetration into the soil, root mass is reduced and plant's ability to take up nutrients is reduced. To test whether cattle congregation sites typical on most forage-based cow-calf ranches, such as mineral feeders, water troughs, and shaded areas are more compacted and have greater soil penetrometer resistance than in other pasture locations under Florida conditions, soil penetrometer resistance data around and beneath three cattle congregation sites in established ($>$10 yr) grazed beef cattle pastures were collected in 2004, 2005 and 2006. Penetrometer readings were collected from two soil depths (0–20 and 20–40 cm) at different locations around the cattle congregation sites following radial (every 90 degrees: north, south, east, and west direction) sampling patterns at 0.9, 1.7, 3.3, 6.7, 13.3, 26.7 and 53.3 m away from the approximate center of cattle congregation sites . Results showed that area around or near cattle congregation sites tended to have higher soil penetrometer resistance values than in other locations within pasture field because of the frequent concentration of cattle around the different cattle congregation sites. Soil penetrometer resistance decreases linearly with distance away from the center of mineral feeders and water troughs; however, soil penetrometer resistance at the shaded areas was showing slight increase with distance away from the center. The least soil penetrometer resistance in all years were observed from shaded areas (1 200 $\times$ 10$^{3}$ Pa) while soil penetrometer resistance at water troughs was about 1 600 $\times$ 10$^{3}$ Pa and at mineral feeders of 1 800 $\times$ 10$^{3}$ Pa. These values were in the “fair” range of root penetration. Penetrometer resistance of soils can be a good predictor of root system performance and especially useful in predicting root extension into the deeper regions of the root zone at the congregation zone and grazing zone in pasture