Influence of nitrogen on atrazine and 2, 4 dichlorophenoxyacetic acid mineralization in blackwater and redwater forested wetland soils

Microcosms were used to determine the influence of N additions on active bacterial and fungal biomass, atrazine and dichlorophenoxyacetic acid (2,4- D) mineralization at 5, 10 and 15 weeks in soils from blackwater and redwater wetland forest ecosystems in the northern Florida Panhandle. Active bacterial and fungal biomass was determined by staining techniques combined with direct microscopy. Atrazine and 2,4-D mineralization were measured radiometrically. Treatments were: soil type, (blackwater or redwater forested wetland soils) and N additions (soils amended with the equivalent of 0, 200 or 400 kg N ha-1 as NH4NO3). Redwater soils contained higher concentrations of C, total N, P, K, Ca, Mn, Fe, B and Zn than blackwater soils. After N addition and 15 weeks of incubation, active bacterial biomass in redwater soils was lower when N was added. Active bacterial biomass in blackwater soils was lower when 400 kg N ha- 1 , but not when 200 kg N ha-1, was added. Active fungal biomass in blackwater soils was higher when 400 kg N ha-1 , but not when 200 kg N ha-1, was added. Active fungal biomass in redwater soils was lower when 200 kg N ha-1 , but not when 400 kg N ha-1, was added. After 15 weeks of incubation 2,4-D degradation was higher in redwater wetland soils than in blackwater soils. After 10 and 15 weeks of incubation the addition of 200 or 400 kg N ha-1 decreased both atrazine and 2,4-D degradation in redwater soils. The addition of 400 kg N ha-1 decreased 2,4-D degradation but not atrazine degradation in blackwater soils after 10 and 15 weeks of incubation. High concentrations of N in surface runoff and groundwater resulting from agricultural operations may have resulted in the accumulation of N in many wetland soils. Large amounts of N accumulating in wetlands may decrease mineralization of toxic agricultural pesticides

Matrix-based fertilizers: A new fertilizer formulation concept to reduce nutrient leaching

We compared the efficacy of matrix based fertilizers (MBFs) formulated to reduce NO 3 -, NH4+ , and total phosphorus (TP) leaching, with Osmocoate® 14-14-14, a conventional commercial slow release fertilizer (SRF), and with an unamended control in greenhouse column studies. The MBF formulations covered a range of inorganic N and P in compounds that are relatively loosely bound (MBF1) to more moderately bound (MBF2) and more tightly bound compounds (MBF3) mixed with Al(SO 4)3 H2O and/or Fe2(SO4 )3 and with high ionic exchange compounds starch, chitosan and lignin. When N and P are released, the chemicals containing these nutrients in the MBF temporarily bind N and P to a Al(SO4 )3 H2O and/or Fe2(SO4 )3 starch- chitosan- lignin matrix. One milligram (8000 spores) of Glomus intradices was added to all formulations to attempt to enhance nutrient uptake. In this first series of experiments, soil columns were planted to white soft spring wheat (Triticum aestivum L.cv. Frame). Three soils were used, a sand, a loam and a loamy sand. In several studies, SRF leachate contained higher amounts of NH4+ , NO3 " and TP than leachate from all other fertilizers. Although plant biomass and yield with MBF was reduced in the first series of experiments, follow-up studies have shown that formulation adjustments allow comparable plant responses among SRF and MBFs. There were no consistent differences in the amount of NH4+ , NO3 - and TP in the MBF leachates compared to the control leachate. Arbuscular mycorrhizal infection in plant roots did not consistently differ among plants growing in soil receiving SRF, MBFs and control treatments. The efficacy of MBF fertilizer strategy to reduce N and P leaching to surface has been verified and with continued work to optimize formulations this technology is expected to provide a new approach for groundwater protection, especially in easily drained soils. The approach has been submitted for patenting

Matrix based fertilizers reduce nitrogen and phosphorus leaching in greenhouse column studies

We tested the efficacy of matrix based fertilizer formulations (MBF) that reduce NH4, total phosphorus (TP), total reactive phosphorus (TRP) and dissolved reactive phosphorus (DRP) in leachate. The MBF formulations cover a range of inorganic N and P in compounds that are relatively loosely bound (MBF1) to more moderately bound (MBF2) and more tightly bound compounds (MBF3) mixed with Al (SO4)3 H2O and/or Fe2(SO4)3 and with the high ionic exchange compounds starch, chitosan and lignin. Glomus interadicies, a species of arbuscular mycorrhizal fungal spores that will form mycorrhizae in high nutrient environments, was added to the MBF formulations to increase plant nutrient uptake. When N and P are released from the inorganic chemicals containing N and P the matrix based fertilizers likely bind these nutrients to the Al(504)3 H2O and/or Fe2(504)3 starch–chitosan–lignin matrix. We tested the efficacy of the MBFs to reduce N and P leaching compared to Osmocote® 14-14-14, a slow release fertilizer (SRF) in sand filled columns in a greenhouse study. SRF with and without Al and Fe leached 78- 84% more NH4, 58-78% more TP, 20-30% more TRP and 61-77% more than MBF formulations 1, 2, and 3 in a total of 2.0 liters of leachate after 71 days. The concentration and amount of NO3 leached among SRF and MBF formulations 1 and 2 did not differ. The SRF treatment leached 34% less NO3 , than MBF3. Total plant weight did not differ among fertilizer treatments. Arbuscular mycorrhizal infection did not differ among plants receiving SRF and MBF formulations 1, 2 and 3. Although further greenhouse and field testing are called for, results of this initial investigation warrant further investigation of MBFs

Matrix-based fertilizers reduce nutrient leaching while maintaining Kentucky bluegrass growth

Abstract We tested the efficacy of matrix-based fertilizers (MBFs) to improve Kentucky bluegrass (Poa pratensis L.) growth while reducing NH, NO3, dissolved reactive phosphorus (DRP), and total phosphorus (TP) compared to commercial slowrelease fertilizer (SRF) Polyon®, ESN®, and Avail® in greenhouse column studies. The MBFs covered a range of inorganic N and P in compounds that are relatively loosely bound (MBF6) and more tightly bound compounds (MBF7) with Al(SO4)318H2O and/or Fe2(SO4)33H2O and with high ionic exchange compounds starch, cellulose, and lignin. The total amount of NO3 and NH4 leached was greater from columns receiving Polyon® and ESN® fertilizers than all other treatments. The MBF6+Avail® or MBF7+ Avail® fertilizers leached 64–68% less NO3 than Polyon® (43-0-0) and ESN® (46-0-0), and 73–76% less TDP and TP than Avail® (10-34-0). A greater amount of NO3 was leached from the MBF6+Avail® and the MBF7+Avail® treatments than the other MBF fertilizer treatments. Shoot and root biomass were greater when plants received the Avail®, MBF6+ Avail®, and MBF7+Avail® fertilizer treatments than the other fertilizer treatments. When combined with small quantities of commercial SRFs, these new MBFs were able to maintain plant growth while reducing N and P leaching. These new MBF formulations do not depend on organic or inorganic coatings to reduce N and P leaching and with further testing and development could be effective commercial fertilizers

Influence of polyacrylamide application to soil on movement of microorganisms in runoff water

Polyacrylamide (PAM) use in irrigation for erosion control has increased water infiltration and reduced soil erosion. This has improved runoff water quality via lower concentrations of nitrogen, phosphorous, and pesticides, and decreased biological oxygen demand. Since non-toxic high molecular weight anionic PAMs removed clay size sediment particles in flowing water, we hypothesized that PAM would effectively remove or immobilize microorganisms in flowing water. In an agricultural field, we determined the efficacy of PAM-treatment of furrow irrigation water to remove several categories of microorganisms in the inflow and runoff. Treatments were: (I) PAM application and a control; (2) three flow rates; (3) two distances from the inflow point; and (4) three times during each irrigation. After water traveled 1 m at 7.5 and 15.5 1 min-1 , PAM-treatment reduced total bacterial and microbial biomass and total fungal biomass relative to the control treatment. After water traveled 40 m at 7.5, 15.5, and 22.5 1 min-1 PAM-treatment reduced algae, the numbers active and total bacteria, active and total fungal length, and total bacterial biomass, total fungal and microbial biomass relative to the control treatment. Although specific organisms were not identified or monitored in this study, the results clearly have implications for controlling the spread of soil-borne plant pathogens and other classes of harmful organisms within and among fields via irrigation water and in re-utilized return flows. Beyond furrow-irrigated agriculture, new methods to manage overland transmission of harmful microorganisms could potentially help control transport of pathogens from animal waste in runoff and groundwater

The efficacy of polyacrylamide to reduce nutrient movement from an irrigated field

Irrigation-induced erosion contributes to elevated sediment and nutrient concentrations in irrigation return-flow water. Polyacrylamide (PAM) is an effective flocculent widely used to reduced soil erosion. We hypothesized PAM would reduce transport of sediment and nutrients in surface irrigation water flowing over soil. We measured nutrients in irrigation inflow and runoff water and total and extractable nutrients in sediment transported from agricultural fields. Treatments were: (1) PAM application and no PAM (control), (2) three flow rates (7.5, 15.0, and 22.5 L min- 1), (3) distance along the furrow (1 m below the inflow point and 40 m down furrow), and (4) time during irrigation (0.5, 3.5, and 6.5 h after initial inflow). After irrigation water flowed 40 m, water flowing in furrows receiving PAM treatments reduced the NO3- concentration in runoff by 85% and the total P concentration in water by 90% compared to runoff water in furrows without PAM, regardless of flow rate. Mass export of NH4 +, NO3-, dissolved reactive phosphorus (DRP), total P, K, Ca, Mg, Fe, Mn, Cu, B, and Zn in untreated irrigation runoff water increased as the flow rate increased from 7.5 to 22.5 L min- 1. Export of these nutrients, via sediment carried by untreated irrigation runoff water, increased from 2 to 5 fold as the flow rate increased from 7.5 to 22.5 L min-1. After water flowed 40 m, transport of these extractable nutrients was reduced from 10 to 40 fold in PAM-treated furrows. With proper application, PAM reduces nutrient loss from furrow-irrigated agricultural fields, protecting surface water and groundwater quality

Matrix based fertilizers reduce nitrogen and phosphorus leaching in three soils

We compared the efficacy of matrix based fertilizers (MBFs) formulated to reduce NO3-, NH4+, and total phosphorus (TP) leaching, with Osmocoate 14-14-14, a conventional commercial slow release fertilizer (SRF) and an unamended control in three different soil textures in a greenhouse column study. The MBFs covered a range of inorganic N and P in compounds that are relatively loosely bound (MBF 1) to more moderately bound (MBF 2) and more tightly bound compounds (MBF 3) mixed with Al(SO4)3H2O and/or Fe2(SO4)3 and with high ionic exchange compounds starch, chitosan and lignin. When N and P are released, the chemicals containing these nutrients in the MBF bind N and P to a Al(SO4)3H2O and/or Fe2(SO4)3 starch-chitosan-lignin matrix. One milligram (8000 spores) of Glomus intradices was added to all formulations to enhance nutrient uptake. In all three soil textures the SRF leachate contained a higher amount of NH4+, NO3- and TP than leachate from all other fertilizers. In all three soils there were no consistent differences in the amount of NH4+, NO3- and TP in the MBF leachates compared to the control leachate. Plants growing in soils receiving SRF had greater shoot, root and total biomass than all MBFs regardless of Al(SO4)3H2O or Fe2(SO4)3 additions. Arbuscular mycorrhizal infection in plant roots did not consistently differ among plants growing in soil receiving SRF, MBFs and control treatments. Although the MBFs resulted in less plant growth in this experiment they may be applied to soils growing plants in areas that are at high risk for nutrient leaching to surface waters

Removal of vegtative clippings reduces dissolved phosphorus loss in runoff

Phosphorus-containing sediment entering surface water may degrade water quality and promote eutrophication. Grass is sometimes planted as a vegetated filter strip buffer along vulnerable receiving water to trap sediment and reduce the severity of phosphorus nutrient loading. However, eutrophication is still a problem in some waterways due to dissolved phosphorus leaching from senesced vegetation in grassed areas, independent of trapped sediment. A rainfall simulator (96 mm/h) was used to study the vegetative conditions under which losses of total dissolved phosphorus and filterable reactive phosphorus leaching are likely. Boxes containing a Portneuf silt loam soil (Xeric Haplocalcid) were planted with annual ryegrass (Lolium perenne) and cut at two different intervals prior to simulated rainfall 14 days apart. Grass clippings were removed from some boxes and retained on others. During the second simulated rainfall, total dissolved phosphorus and filterable reactive phosphorus in runoff were significantly greater for treatments cut the day before irrigation (0.95 and 0.74 mg/L, respectively) with clippings retained as compared to treatments cut the same day as irrigation with clippings retained (0.74 and 0.59 mg/L, respectively). Removing clippings yielded the lowest mean concentration for both total dissolved phosphorus and filterable reactive phosphorus (0.56 and 0.39 mg/L, respectively). Increasing the senesced vegetative surface area for contact with water, and the amount of time for leaching to occur, resulted in the greatest filterable reactive phosphorus loss. Results point to the potential for vegetation management programs to impact runoff water quality from vegetated buffers. Thus, management implications for vegetated filter strips should consider clippings removal, or perhaps no or reduced mowing during the growing season followed by end-of-season removal, to reduce filterable reactive phosphorus leaching losses

Compost amendments decrease Verticilliuam dahliae infection in potato

Indigenous soil microorganisms contribute to disease suppression in cropping systems by reducing and competing with pathogen populations, thereby limiting disease severity. Various communities of indigenous microorganisms in any particular soil have adapted to the specific environmental conditions. If the soil around the plant roots could be altered to favor the indigenous soil microorganisms relative to the plant pathogen, the survival and proliferation of indigenous soil microorganisms, and thus effectiveness of biological control, may be increased. Wood chip-polyacrylamide (PAM) cores were used to alter the soil environment in a greenhouse study to favor indigenous soil microorganisms in vegetable and manure compost to reduce Verticillium dahliae infection of potato (Solarium tuberosum L.) plants. Potato plants growing in soils amended with vegetable compost-wood chip-PAM cores had significantly lower visible (V vis,) and isolation (V iso) dahliae infection rates than control soils and soils with dairy or vegetable compost alone. Soils amended with wood chip-PAM-dairy compost cores had significantly lower IC and isolation V. than control soils and soils with dairy compost. Soils with wood chip-PAM cores and soils with wood chip-PAM-vegetable compost had greater microbial biomass/ Verticillium dahliae biomass (MB/ VB) ratios in soil than control soils or in soils amended with compost alone. MB / VB ratios in wood chip-PAM cores and wood chip- PAM-vegetable compost were greater than in wood chip-PAM-dairy compost cores. V correlated in a quadratic relationship with the MB /VB ratio (r 2=0.76). As MB /VB ratio increased Although field studies with several crops and economic evaluations are necessary, this greenhouse study provides evidence that a wood chip-PAM or wood chip- PAM-vegetable compost soil amendment may be a viable method to control some soil diseases in high value crops

Wood chip-polyacrylamide medium for biocontrol bacteria decreases Verticillium dahliae infection on potato

The lack of consistent success of biological control of soilborne plant pathogen's may be due to the introduction of the organism into a foreign environment. We hypothesized that wood chip-polyacrylamide ( PAM) cores surrounding host plant roots could alter the soil environment to favour growth of introduced biocontrol microorganisms, thereby reducing Verticillium dahliae infection of potato (Solanum tuberosum L.) in a greenhouse. A 7 cm diameter x 15 cm deep hole (core) was drilled in the center of a 20 x 30 cm deep pot ( 1.9 kg) containing soil infested with V. dahliae inoculum. Cores were then filled with wood chip-PAM-biocontrol organism mixtures. Soils that had Streptomyces lydicus inoculated into wood chip-PAM cores had lower levels of V. dahliae symptoms (Vvis) and V. dahliae isolations (Viso) than all other treatments in three soils. Vvis and Viso on plants growing in soils amended with S. lydicus or Pseudomona corrugata inoculated into the soil itself (without wood chip-PAM cores) did not differ from soils that were unamended with these biocontrol organisms. V. dahliae biomass was lower in wood chip-PAM cores inoculated with S. lydicus than control or wood chip-PAM cores without biocontrol bacteria. Soils with wood chip-PAM cores inoculated with S. lydicus or P. corrugata generally had higher microbial biomass/V. dahliae biomass (MB/VB) ratios than control soils, or soils with S. lydicus or P. corrugata inoculated into the soil. Wood chip-PAM cores alone and wood chip-PAM cores inoculated with S. lydicus had higher MB/VB ratios than wood chip-PAM cores inoculated with P. corrugata. Vvis and Viso were curvilinearly correlated with the MB/VB ratios in negative relationships, respectively (r2 = 0.68, r2 = 0.68). As the MB/VB ratio increased, Vvis and Viso decreased. Although field studies and economic evaluations are necessary, amending soil with wood chips-PAM and a biocontrol bacterium may be a valuable method to increase the effectiveness of biocontrol organisms