The theory and practice of slow-release fertilizers have been reviewed by Hauck and Koshino. This chapter deals with enough background information to place coated fertilizers in their proper relationship with other slow-release products and reviews published information on forage fertilization with coated fertilizers. Potential benefits from controlled release fertilizers include: increased efficiency of nutrient use by the crop, decreased leaching of nutrients from coarse textured soils, lower toxicity, and longer lasting nutrient supply, thus requiring fewer applications. Controlled release fertilizers are of three types or combinations thereof: biodegradable organic compounds, compounds of low solubility that release nutrient by slow dissolution and/or hydrolysis, and coated soluble sources. Small field trials with S-Coated Urea (SCU) prepared by the TVA process have been under way for more than 5 years. With recent development of a pilot plant capable of producing 1 ton per hour, SCU will be available for more extensive testing.

Soil management practices can alter the natural balance at the soil-plant-atmosphere ecosystem interface, which can significantly affect the environment. This study compared CO2 fluxes in conventional tillage (CT) and no-tillage (NT) corn (Zea mays L.) production systems receiving poultry litter (PL) and ammonium nitrate (AN) fertilizers on a Decatur silt loam soil in the Tennessee Valley region of North Alabama from Spring 2008 to Fall 2009. Soil CO2 flux in CT plots (9.5 kg CO2 ha(-1) day(-1)) was significantly greater than that in NT plots (4.9 kg CO2 ha(-1) day(-1) in summer. Soil CO2 fluxes were lowest in fall where CT plots had a mean soil CO2 emission of 0.8 kg CO2 ha(-1) day(-1), while plots under NT and grass fallow system were sinks of CO2 with fluxes -0.6 and -1.0 kg CO2 ha(-1) day(-1), respectively. Mean soil CO2 flux averaged over seasons in NT plots was 36% lower than that in CT plots. Grass fallow plots were net sinks of CO2 with a mean CO2 flux of -0.4 kg CO2 ha(-1) day(-1). Our study showed that application of PL or AN fertilizer in NT systems can significantly reduce soil CO2 emissions compared to CT systems in corn production.

ABSTRACT Land application of poultry litter as fertilizer may lead to impaired surface and ground water quality. An experiment was conducted at Crossville, AL to study the effects of alum [Al2(SO4)3 · 14H2O] treatment of broiler litter on the yield and nutrient uptake of tall fescue (Festuca arundinaceae) and the nutrient content of runoff water exited from treated plots. Alum was used at the rate of 0, 545 and 1090 kg per 1464 m2 (12 m × 122 m) of the poultry house. The low rate is the one recommended by Natural Resource Conservation Service (NRCS) in Alabama. Soil samples were collected from the research plots at the beginning of the experiment and at the end of each growing season from 0–7.5, 7.6–15, and 16–30 cm depth. Runoff samples were collected from each plot after each rainfall event that caused runoff. Alum treatments had no effect on tall fescue dry matter yield, and the herbage nutrient concentrations were within acceptable limits. We observed significant reductions in the runoff concentrations of NH4-N (28.6 mg L−1 for untreated litter vs. 15.0 mg L−1 for alum-treated litter), total P (11.5 mg L−1 vs. 5.1 mg L−1), soluble reactive P (10.4 mg L−1 vs. 4.7 mg L−1), and particulate P (1.9 mg L−1 vs. 0.8 mg L−1). This practice should receive serious consideration as a method of reducing the adverse environmental impact of broiler chicken production when the litter is applied to pasture land.

Renewable energy sources such as bioenergy crops have significant potential as alternatives to fossil fuels. Potential environmental problems arising from soil sediment and nutrient losses in runoff water from bioenergy crops need to be evaluated in order to determine the sustainability and overall feasibility of implementing bioenergy development strategies. This paper discusses runoff, sediment, N, and total P losses from agricultural land (continuous cotton (Gossypium hirsutum L.)) converted to short-rotation sweetgum (Liquidamber styraciflua L.) plantations with and without fescue (Festuca elatior L.) and switchgrass (Panicum virgatum L.) bioenergy crops, compared to corn (Zea mays L.), on a Decatur silt loam soil in north Alabama, from 1995 to 1999. Runoff volume was significantly correlated to total rainfall and sediment yield in each year, but treatment differences were not significant. Sweetgum plots produced the highest mean sediment yield of up to 800kgha−1compared to corn and switchgrass plots, which averaged less than 200kgha−1. Runoff NH4+ N losses averaged over treatments and years for spring season (3.1kgha−1) were three to five times those for summer, fall, and winter seasons. Runoff NO3− N for no-till corn and switchgrass plots in spring and summer were five to ten times that for sweetgum plots. No-till corn and switchgrass treatments had 2.4 and 2.1kgha−1 average runoff total P, respectively, which were two to three times that for sweetgum treatments. Growing sweetgum with a fescue cover crop provides significantly lower risk of water pollution from sediment, runoff NH4+ N, and NO3− N.

ABSTRACT The scientific community and various environmental groups have been concerned about the leaching of nitrate (NO3) to ground water from various sources including crop fields where all the applied NO3 is not utilized by the primary crop. Experiments were conducted on two soil types in Alabama to investigate the use of winter cover crops to capture NO3 remaining after the harvest of corn, cotton and soybeans. In these experiments, harvest of the primary crops was so late that cover crop growth in the fall was insufficient to immobilize significant amounts of NO3. Soil testing the following spring showed that most of the soil NO3 was in the top 30 cm (12 in) of the soil profile. A subsequent cover crop planting date experiment showed that wheat planted after September 18 and rye planted after October 2 made insufficient fall growth to immobilized significant amount of NO3. Most spring growth occurred after late February when much of the winter rainfall had already occurred. It appears that judicious selection of nitrogen fertilizer rates is a better approach to reducing NO3 leaching.

Berm-isolated (0.5 ha) plots have been used since 1995 to quantify changes in soil and water quality with conversion from agricultural to bioenergy crops. Soil quality improvements, including increases in soil carbon storage, have occurred on sites planted to woody or herbaceous species, and no-till corn compared with tilled corn or cotton. Initial increases in soil carbon occurred within the upper 10 cm of the soil profile. Soil carbon on plantings of switchgrass, no-till corn, and sweetgum with a cover crop between the rows increased over the first 3 years. Soil carbon decreased by 6% on the sweetgum plantings without a cover crop and remained lower through the fifth growing season. Overall, the greatest increases in belowground carbon storage have occurred primarily within the upper 40 cm. Former land use, growth characteristics, management practices, and soil characteristics appear to be the primary factors determining the timing, depth, and extent of changes in soil carbon storage for bioenergy and no-till crops.

In the southeast, soybean and grain sorghum ar e impor­ tant crops, and ther e is a need to determine the ef fects of tillage, weed contr ol methods, and r ow spacing on soil properties and yield of these cr ops. The objectives of this research were to determine the effects of thr ee weed control methods (none, cultivation, and herbicides) and three row spacings (45, 60, and 90 cm) on no-till (NT), planted grain sorghum (after wheat and clover), conven­ tionally planted soybeans and no-till in wheat stubble for two growing seasons. NT planted soybeans pr oduced 3102 kg ha -1 , 2911 kg ha and 2216 kg ha -1 seed with

Effects of varying strip widths of four species of cover crops on the growth of sweetgum (Liquidambar styraciflua L.) seedlings planted as a short-rotation bioenergy woody crop were studied. Ryegrass (Lolium multiflorum L. a winter annual grass); tall fescue (Festuca arundinacea Schreb a cool-season perennial grass); crimson clover (Trifolium incarnatum L. a winter annual legume); and Interstate sericea lespedeza (Lespedeza cuneata (Dumont) G. Don. a summer growing perennial legume), were planted using two different strip widths (1.22 and 2.44m) between trees on a 1.5×3m spacing. The control had no competition. Height, ground-line diameter and volume index of trees were determined on a monthly basis. Lespedeza and tall fescue significantly reduced ground line diameter, height and volume index compared to ryegrass and the control. Crimson clover significantly reduced ground line diameter compared to the control and volume index more than ryegrass and the control. During first two growing seasons, there was no benefit from legumes as a cover crop over grasses. All cover crops except rye grass significantly reduced sweetgum biomass compared to control. The results indicate that cover crops lespedeza, tall fescue, crimson clover and ryegrass reduced biomass by approximately 41%, 37%, 27% and 15%, respectively, compared to the control. The 2.44m strip width reduced sweetgum growth 40% relative to the control vs. 20% with the 1.22m strip width. Strip width had a greater impact on diameter and volume index than height.

Understanding the interrelationships that exist in a soil is the key to understanding processes like, soil erosion. Notably, the severity of soil erosion will vary, depending on a number of factors. Among the most influential are soil physical and hydraulic properties and their spatial distribution. In this particular study, soil physical and hydraulic properties were characterized spatially for both agricultural and forest vegetated areas. The study site, which was located at the Winfred A. Thomas Agricultural Research Station, in Hazel Green, Alabama consisted of two blocks and each block contained four differently conditioned plots. The land use practices implemented were corn, switchgrass, sweetgum trees, and sweetgum trees with tall fescue grass as a cover crop. To examine the spatial distribution of soil properties, analyses were conducted to determine properties like, soil pH, texture, bulk density, and hydraulic conductivity for each land use practice. Interestingly, pH, bulk density, and water retention were all highest in the corn plots and lowest in the sweetgum tree plots with fescue as a cover crop. Contrastingly, the sweetgum tree plot with fescue had the lowest bulk density and the highest hydraulic conductivity

This study was designed to test whether the cultivation of cover crops between tree rows in short-rotation woody crop (SRWC) plantations could reduce erosion. Sweetgum (Liquidambar styraciflua L.) seedlings were planted as the SRWC at a 1.5 x 3 m spacing. Four cover crops, annual ryegrass (Lolium multiflorum L. a winter annual grass); tall fescue (Festuca arundinacea L. a cool-season perennial grass); crimson clover (Trifolium incarnatum L. a winter annual legume); and Interstate sericea lespedeza [Lespedeza cuneata (Dumont) G. Don. a summer growing-perennial legume], were tested at two different strip widths (1.22 and 2.44 m) in comparison with complete competition control. Erosion was measured from 1 August, 1995 to 8 March, 1997 (585 days) by sediment accumulation near the fence where 72 PVC pipes were inserted into soil on a 4.65 m(2) (50 ft(3)) grid area of each plot. The total rainfall recorded during this period was 2422.91 mm (95.3 in.). All cover crops reduced erosion over the complete competition free plot (control), although tall fescue performed poorly at the narrow strip width. There were no significant differences between grasses and legumes for erosion control. Winter annual crops provided significantly more erosion protection than summer growing-perennials. With the exception of tall fescue, narrow strip widths performed as well as wider strip widths. The results indicate that cover crops ryegrass, crimson clover, lespedeza and tall fescue controlled about 64, 61, 51 and 37% soil erosion respectively as compared to the control during the critical early years of stand development in SRWC hardwood plantations. (C) 2000 Elsevier Science Ltd. All rights reserved.

Ensuring acceptance of dedicated biomass feedstocks by landowners, agricultural communities, environmental and public interest groups, requires that the environmental benefits, concerns, and risks associated with their production be quantified. Establishment and management measures to benefit soil and water quality are being identified by ongoing research. Field studies are showing that nutrients are retained within the rooting zone of dedicated feedstocks, subsurface herbicide transport does not occur, and off-site chemical transport is minimal compared with traditional agricultural crops. The amounts and timing of fertilizer application were critical to minimizing offsite transport of nutrients. Maintaining soil cover decreased runoff, sediment losses, and nutrient transport compared with traditional agricultural crops. Conversion of traditional croplands to biomass and no-till crop production improved soil quality and soil carbon storage. Subsurface nutrient losses were less from biomass crops than adjacent natural forests or agricultural crops in Minnesota. Data across the spectrum of climates and soils from North to South show initial gains in soil carbon are greater at shallow depths (0-10 cm) and in lower organic soils. Addressing environmental questions across planting scales and documenting changes in soil and water quality with biomass crop production on former agricultural lands is critical to identifying production options to (1) maximize environmental quality, (2) minimize environmental risks, and (3) ensure economic benefits for growers.

The development of conservation tillage systems for cotton (Gossypium hirsutumL.), capable of reducing soil erosion and improving soil quality while increasing yields and profits, remains a challenge in the southeastern USA. Poor emergence and growth, delayed maturity, and reduced yield are some of the problems that have been encountered in the use of conservation tillage on cotton. The objectives of this study was to evaluate the effects of tillage (no‐till, mulch‐till, conventional till), cropping system [cotton–winter fallow, cotton–winter rye (Secale cerealeL.) cover crop] and N source (poultry litter, ammonium nitrate) on growth and yield of cotton from 1996 to 1998 in northern Alabama. In 1997, cotton lint yield under no‐till (NT) was 24 and 18% greater than that under conventional till (CT) and mulch‐till (MT) systems, respectively. In 1998, cotton lint yield under the NT system was 7% greater than that under CT. Poultry litter (PL) at 100 kg N ha−1gave similar lint yield to ammonium nitrate (AN), whereas at 200 kg N ha−1, lint yields were significantly greater. No‐till, cotton–winter rye cropping, and surface application of 200 kg N ha−1in form of PL conserved soil moisture in the top 7 cm of the soil. This resulted in early seedling emergence, high seedling vigor, good plant growth, and high lint yield of cotton. These treatments would be appropriate for use in the southeastern USA where soil erosion is a problem and plenty of PL is available each year from the poultry industry.

The main objectives of this study were to determine the biogeochemical changes taking place in wetlands constructed on coal mine spoil, and to determine the rate at which these constructed wetlands would develop the ecological characteristics of natural wetlands. In 1992 a multicell wetland was constructed. The cells were lined with two coal mine spoil types and one topsoil. In 1993, the cells were planted with cattail (Typha latifolia), maidencane (Panicum hemitomon), pickerelweed (Pontederia lanceolota), and soft stem bulrush (Scirpus validus). Pickerelweed spread most rapidly followed by maidencane and bulrush. Cattail did not establish uniformly but spread in an irregular manner. There was no difference in plant establishment between the topsoil or the two mine spoils. The pH of the most acidic spoil increased by more than one unit after flooding. Organic matter content fluctuated in all three substrates from year to year. The concentration of the nutrient and metal elements increased after flooding. Extractable Al, Fe, and Mn increased more than other elements. The data presented here indicate that, except for organic matter accumulation, these constructed wetlands have taken on the botanical and biogeochemical characteristics of natural wetlands within 3–4 years.

: Erosion causes many environmental and property damage problems along the shorelines of natural and man-made lakes. The research reported here was conducted at the Walter F. George Reservoir which lies between Georgia and Alabama. The lake is characterized by water level fluctuations of 5 or more feet and occasional strong wave actions. Beginning in 1994, several experiments were conducted using biotechnical methods to control damage from wave action. Coconut fiber logs, straw bales wrapped in poultry netting, large round hay bales, and bundled logs anchored to the shoreline were all evaluated for their potential to control wave damage to the shoreline. While these materials were effective at normal water levels in calm weather all eventually failed either because of excessive flooding or storm driven wave action. Several species of wetland and terrestrial plants were planted behind the breakwaters with short term success but all were destroyed by wave action when the breakwaters failed. A greenhouse experiment using substrate from the site showed a strong response to fertilizer nitrogen by both wetland and terrestrial plants.

Except where a good legume sod is plowed under or a heavy application of manure is used, N fertilizer applications are generally necessary for producing high yields from grain crops. A soybean (Glycine max (L.) Merr)-wheat (Triticum aestivum L.) rotation appears to be a logical opportunity to use legume N as a sustainable grain production resource. An experiment conducted to compare N from soybeans with fertilizer N resulted in a 46% reduction in wheat yield following soybeans where wheat was not fertilized with N. Subsequent research showed that when soybeans were allowed to grow to bloom stage or later preceding a wheat or triticale (x Triticosecale Wittmack) crop a significant reduction in grain yield resulted from the previous soybean crop. When the grain crop was fertilized with 80 lbs/acre of N this response did not occur. The experimental results suggest that soybean root exudates are responsible for the decrease in wheat and triticale growth and yield.

More information on the response of newly developed or introduced grain sorghum cultivars to split-applied nitrogen (N) in semi-arid rainfed agriculture is needed. Therefore, the influence of four split-applied N schedules (100/0, 66/34, 50/50, and 34/66) on six American (SC 283, SC 274, SC 669, B 66181, SC 33, and RTam 428), and four West African (CSm 63, IS 6704c, 1S 7173c, and 1S 7419c) grain sorghum cultivars was evaluated. The split-applied N significantly increased grain yield and percent protein in grain sorghum over a one-time application of N. The increase in yield and protein content varied among varieties and schedules of N application. Varieties SC 574, RTam 428, and Csm 63 at split-applied schedules of 66/34, 50/50, and 34/66, respectively, gave the highest yield over one-time application of N. Similar differences in percent protein in grain among cultivars due to split-applied N were observed.