The extent of agricultural drainage has created concern for its potential undesirable effects on surface water quality. Land applications of liquid manure on tile drain fields have the potential to transport solutes and bacteria to the drains following precipitation or irrigation events and many times are directly sent to a surface water body, and have been documented as a source of contamination of surface waters. This study determined the potential for and magnitude of E. coli and solute migration to tile drains through the soil profile. Water from subsurface drains was analyzed for chemical and bacterial composition following tracer applications. Two sites were selected for the study to determine transport at large (field) and small (plot) scales. At the large-scale site, both tracers, bacteria (E. coli and Total Coliform) and Amino-G (a conservative tracer), were used to monitor the speed of transport from the surface to the tile drain following liquid manure applications, tracer applications and additionally precipitation events. The concentrations of E. coli were monitored every hour for 76 days during the spring. Both tracers, bacteria and Amino-G, were detected in the tile drainage shortly after precipitation events. The peak concentration of E. coli was observed to be 1.2 x 10⁶ CFU/l00mL. These elevated concentrations of E. coli might be attributed to the characteristics of the soil, high organic matter and well-structured clay soils. Both the rapid breakthrough of tracer to the tile drain and the peaks of tile water temperature during precipitation events provided evidence of macropore flow. Antecedent soil moisture and warmer temperatures appeared to provide ideal conditions for bacteria growth. The small-scale study site was selected for a more focused study. The purpose of this site was to quantify more accurately the percent mass of surface applied tracer that was transported to the tile drain, allowing mass balance calculations. Experiments were conducted during the summer to control the rate and total amount of irrigation. Amino-G readings were taken every 10 seconds for 125 hours of continuous irrigation. Tracer applications were conducted at runoff and non-runoff conditions. Both types of tracer applications had Amino-G breakthrough in less than 10 minutes after initiation of irrigation. Tracer applied at runoff rates resulted in 4 to 17 times more total tracer mass migrating to the tile drain than when applied at non-runoff rates. The total mass of Amino-G migrating to the tile drain during non-runoff conditions depended on the total volume of applied tracer, regardless of the tracer concentration. For an application of 5.6 mm at 12 mg/L, 5.7% of the total applied tracer migrated to the tile drain, whereas for an application of 1.9 mm at 27.7 mg/L only 2.8% of the total applied tracer migrated to the tile drain. Tile flow response to irrigation experiments appeared to be governed by soil moisture. Lysimeter samples were taken continuously every 4-8 hours until the 94th hour after tracer application. Tile water concentrations were consistently greater than concentrations found in the deeper suction lysimeters at corresponding times, providing further evidence of preferential flow. E. coli transported through the soil and into the drains were demonstrated to be event-driven by precipitation events and irrigation events. In addition, the characteristics of this type of soil - the high clay content, the well-defined structure, the high level of organic matter and rich biological activity has been known to enhance the preferential pathways and transport processes in the soil profile, resulting in rapid transport of surface applied solutes and effluents to tile drains. / Graduation date: 2003

Thesis (MTech. degree in Agriculture)--Tshwane University of Technology, 2011.

No description available.

Laboratory studies and field trials were carried out to investigate the effect of addition of some organic residues to acid soils on soil pH, exchangeable and soluble AI, nutrient status, microbiological and biochemical indices and maize response. The organic wastes used in the first laboratory study included plant materials (maize. sorghum, kikuyu grass, soybean, red clover residues and acacia prunings), animal manures (kraal, pasture-fed and feedlot cattle manure, layer and broiler poultry manure and pig manure), household compost, sewage sludge, and filter cake. The poultry manure, pig manure and leguminous plant residues had the highest content of basic cations while sewage sludge had the highest N content. Poultry manure had very high values for proton consumption capacity, CaC03 content and ash alkalinity. Proton consumption capacity, ash alkalinity, total basic cation content and CaC03 content were closely correlated with one· another. Soil pH was increased and exchangeable AI and total (AIT) and monomeric (AIMono) AI in solution were decreased by addition of all the organic wastes: the effect was greater at the higher rate of application. Strong correlations were recorded between the rise in soil pH and proton consumption capacity, ash alkalinity, CaC03content and basic cation content of the residues. The major mechanisms responsible for the elevations in pH were suggested to be the substantial CaC03content of poultry and pig manures, and filter cake, the proton consumption capacity of humic material present in household compost and manures and decarboxylation of organic acid anions during the decomposition of plant residues and manures. It was proposed that ash alkalinity is a suitable laboratory test for predicting the potential Iiming effect of organic residues since it is strongly correlated with the rise in pH that occurs, it is relatively simple to measure and the values reflect the initial content of organic acid anions, humic materials and CaC03in the residues. A preliminary field experiment was set up to investigate the effectiveness of kraal manure as a Iiming material in an acid soil (pHwater =4.1) at a site close to a Zulu village. The experiment consisted of two rates of lime (L1 = 2.5 and L2 = 5.0 t ha1) and two rates of kraal manure (K1 = 10 and K2 = 20 t ha-1 ) which were banded and incorporated in a 30 cm wide strip down the plant rows. Treatments were arranged in a randomized block design with three replicates. A commercial maize cultivar PAN 6710 and a traditional variety EMBO, used by the farmers in the locality, were grown. Soils in the plant row were sampled at tasselling and at harvest. The addition of kraal manure significantly raised soil pH and reduced concentrations of exchangeable AI and those of both total and monomeric AI in soil solution. Lime raised pH and the pH continued to increase between tasselling and harvest. Maize yields for control, kraal manure (K1 and K2) and lime (L1 and L2) for PAN 6710 were 2.5, 3.7, 5.1, 5.3 and 6.3 t ha-1 ; respectively and for EMBO they were 3.0, 5.4, 5.8, 5.9and 8.2 t ha-1 , respectively. These results demonstrate the high yield potential of the traditional maize variety under small scale farming conditions, and show that large yield increases can be obtained by applying kraal manure. The long-term effects (24 weeks) of incubation of organic wastes (soybean residues, poultry, pig and kraal manures and sewage sludge) with an acid soil were investigated in a laboratory study. After incubation for six weeks incubation, soil pH was raised and exchangeable AI and Air and AIMono in soil solution were decreased . by addition of the wastes. Soil pH generally declined and exchangeable and soluble AI increased over the remainder of the incubation period. The decline in pH was attributed mainly to nitrification of NH4+ originating from mineralization of wastes-derived organic N. Addition of organic materials generally resulted in a decrease in the proportion of solution Air present as AIMono. That is, the effects of addition of organic materials was two-fold; an increase in pH in the short term and complexation of AI by organic matter. Since these effects occur simultaneously, it would be desirable to separate them. For this reason, short-term equilibration experiments (3 days) were conducted to study the solubility of AI in aqueous solution or in an Oxisol when in equilibrium , with 3 manures (kraal, pig and poultry) at pH values of 4.0, 4.5, 5.0, 5.5, 6.0 and 6.5. Addition of manures tended to reduce the concentrations of total AI in solution (AIT) in the lower pH range (Le. pH 4.0 and 4.5) but increased AIT concentrations compared to the control, at higher pH values (Le. at pH 5.5 and above). This was explained in terms of the complexing ability of both the solid and solution phases. At lower pH, where AI is highly soluble, complexation by added solid phase manure-organic matter results in a reduction of AI solubility. However, at high pH, where AI solubility is limited, the most important mechanism is complexation of AI by soluble organic matter and this increased AI solubility. Additions of manure reduced the proportion of Air present in monomeric form (AIMono). This effect was more pronounced in aqueous solution but was also clearly evident above pH 5.0 in the Oxisol. This reflects the fact that a large concentration of soluble C in solution can maintain relatively high concentrations of complexed AI in solution but at the same time maintain low concentrations of AIMono. It was concluded that formation of AI-organic matter complexes caused by additions of organic manures can alter the solubility of AI and reduce the amount of phytotoxic AIMono present in soil solution. A second field trial was conducted to compare the effects of additions of kraal manure, grass residues, lime and fertilizer (N-P-K) under field conditions, on soil pH, AI solubility and maize response and, at the same time follow concomitant changes in the size and activity of the soil microbial biomass and enzyme activity. The greatest effects of kraal manure in increasing soil pH and decreasing AI toxicity were recorded six weeks after planting whereas those of lime and grass residues were recorded at harvest. Kraal manure and fertilizer increased significantly AMBIC extractable P and exchangeable K and Zn. In addition, Kraal manure, and to a lesser extent lime significantly increased exchangeable Ca and Mg.. Soils in the plant row in the grass residue treatments had the highest microbial biomass C and microbial quotient,followed by kraal manure, lime and controls. Basal respiration rates and arginine ammonification, protease, aryl sulphatase, and acid phosphatase activity rates were significantly increased by addition of all treatments and these increases tended to be accentuated by fertilizer. Low values for metabolic quotient in the grass residue treatments were associated with high values for microbial biomass C in these treatments. The addition of all treatments tended to increase maize yields and, in general, these yields were greater for the high rate of application of each amendment. Yields for unfertilized kraal manure were markedly greater than those for the unfertilized grass residue and lime treatments. This was attributed to the ability of kraal manure to both increase pH and add nutrients to the soil. / Thesis (Ph.D.)-University of KwaZulu-Natal, Pietermaritzburg, 2004.

The effect of serial (multiple-year) organic matter (OM) amendment on soil properties has been described in some cropping systems, although less is known about the effect of serially amended field soils on soil-borne plant diseases. The objectives of this study were to describe the effects of the third and fourth years of annual, serial amendment with dairy manure solids on 1) soil physical and biological properties and 2) severity of sweet corn root rot. Plots were amended with five rates of separated dairy manure solids annually for three years. In the fourth year, plots were split and only half of each plot was re-amended. Soil physical properties [bulk density, free and occluded particulate organic matter (POM), soil water retention, total porosity, gravimetric moisture content] and biological properties [microbial activity (as hydrolysis of fluorescein diacetate; FDA) and microbial biomass-C] were assessed each year in all treatments. Root rot severity was assessed in situ and in the greenhouse with multiple sweet corn (Zea mays L. cv Golden Jubilee) bioassays conducted in the amended field soils. Necrosis of the radicle and nodal roots was assessed when plants reached the 6- leaf stage. Amendment rate was positively associated with increases in soil properties that serve as indicators of soil quality, such as POM content, total porosity, microbial biomass, and FDA activity. In the third year after amendment, weak root rot suppression was observed in-field and was associated with FDA activity. By the fourth year of serial amendment this trend was no longer evident, however evidence from the high-rate treatment that was not re-amended (3HNRA) pointed to an emerging suppressive mechanism that persisted up to 13 months after the third amendment. Factors that may be interacting over time to generate observed disease suppression in these serially amended soils include: short-term post-amendment microbiostasis, soil moisture retention, inoculum potential, and a novel suppressive mechanism. / Graduation date: 2006

Diss. (sammanfattning). Uppsala : Sveriges lantbruksuniv., 2003. / Härtill 4 uppsatser.

Diss. (sammanfattning) Uppsala : Sveriges lantbruksuniv., 2003. / Härtill 4 uppsatser.

Thesis (Ph. D.)--Michigan State University. Crop & Soil Sciences, 2008. / Title from PDF t.p. (viewed on Aug. 17, 2009) Includes bibliographical references. Also issued in print.

Made available in DSpace on 2014-06-11T19:32:26Z (GMT). No. of bitstreams: 0 Previous issue date: 2009-05-29Bitstream added on 2014-06-13T19:22:05Z : No. of bitstreams: 1 almeida_k_dr_botfca.pdf: 947058 bytes, checksum: 95e2f811c6edc422916d6f1245c2c2a1 (MD5) / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES) / O presente trabalho objetivou estudar o efeito das plantas de cobertura crotalária (Crotalaria juncea), feijão-guandu (Cajanus cajan), feijão-de-porco (Canavalia ensiformes), milho (Zea mays), milheto (Pennisetum glaucum) e mucuna-preta (Mucuna aterrimum), em cultivo exclusivo e consorciado, e vegetação espontânea, no desempenho agronômico de alface (Lactuca sativa) e cenoura (Daucus carota) cultivadas em sistema orgânico. Para tanto, foram conduzidos três experimentos, sendo um referente à seleção das espécies utilizadas como adubo verde. O primeiro e segundo, determinaram as quantidades de palhada para a formação de cobertura morta, além da decomposição e liberação de nutrientes das palhadas. O terceiro, o efeito do pré-cultivo de leguminosas e gramíneas no rendimento de alface e cenoura cultivadas em sistema orgânico. O delineamento utilizado nos dois primeiros experimentos foi o de blocos casualizados com quatro repetições, e o terceiro experimento em esquema de parcelas divididas (alface e cenoura). Nos estudos da decomposição e liberação de nutrientes das palhadas foi utilizado o método da “litter bags”. Conclui-se que o feijão-deporco em cultivo exclusivo apresentou maior produtividade de massa fresca, que os demais adubos verdes, e juntamente com o coquetel completo, maior produtividade de massa seca e acúmulo de nutrientes para a cenoura e alface. O uso de adubos verdes em pré-cultivo das oleráceas manteve a produtividade da cenoura semelhante à testemunha.Dentre as espécies utilizadas, o feijão-de-porco em cultivo exclusivo proporcionou melhor rendimento comercial da alface. Pelos resultados dos experimentos, detectou-se que a adubação verde é uma prática promissora para a produção orgânica de alface e cenoura. / The present work objectived to study the effect of cover crops with Crotalaria juncea, Cajanus cajan, Canavalia ensiformes, Zea may, Pennisetum glaucum, and Mucuna aterrimum, in single and associated cultivation and spontaneous vegetation, in the agronomic performance of lettuce (Lactuca sativa) and carrot (Daucus carota) under organic system. Three experiments were conducted, the first one referring to the selection of the species used as green manure. First and second experiments determined the amounts of straw production of phytomass, besides the decomposition and nutrient release of the straws. The third one, the effect of the legumes and grasses pre-cultivation in the lettuce and carrot yields under organic system. The experimental design was a randomized block with four repetitions in the two first tests and the third test a split-splot (lettuce and carrot). In the studies about decomposition and nutrient release of the straws it was used the method of litter bags. It was concluded that Canavalia ensiformes in single cultivation shows higher productivity of fresh mass than other green manure and in complex with the complete cocktail, higher productivity of dry mass and nutrient accumulated for carrot and lettuce. The use of the green manure in pre-cultivation of the vegetables maintained the carrot productivity similar to the no-treated. Among the species of green manure Canavalia ensiformes in single cultivation promoted the best commercial yields of lettuce. By the results, it was detected that the green manure is a promising practice to the organic production of lettuce and carrot.Key words: green manures, legumes, Lactuca sativa, Daucus carota.

Made available in DSpace on 2014-10-09T12:45:20Z (GMT). No. of bitstreams: 0 / Made available in DSpace on 2014-10-09T14:06:17Z (GMT). No. of bitstreams: 1 07177.pdf: 26753292 bytes, checksum: 81a931adb15e4e0a05ed87c5b6230b93 (MD5) / Dissertacao (Mestrado) / IPEN/D / Instituto de Pesquisas Energeticas e Nucleares - IPEN/CNEN-SP