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High-biomass cover cropping enhances marketable yields in organic production of vegetables, linked to the improvement of soil quality and weed control. Although, during transition from chemical to organic cover-cropping production, especially with no-till systems, reduction of nitrogen availability to the main crop and increase in weed and pest pressure may occur. In 2004-2005, summer and fall broccoli (Brassica oleraceae L. Botrytis Group) crops were grown in twin rows on permanent (controlled traffic) raised beds (185-cm wide). Before broccoli transplanting, high-biomass cover crops were grown in specific bed areas. Legumes (Vicia villosa, Glycine max L., and Crotolaria juncea L.) on bed tops (grow zones) and grass species (Secale Cereale L., Setaria italica L., and Sorghum bicolor X S. bicolor var. Sudanese) in the alleyways (bed shoulders and bottoms). Experimental treatments were tillage (conventional, CT; and no-tillage, NT), farmscaping (with and without), and nitrogen sidedressing (with and without, applied 3 weeks after transplanting as a mixture of sodium nitrate - 22 kg N ha-1 - and feathermeal - 44 kg N ha-1). Weeds were managed by mechanical cultivation in CT and a spot weeding by hand in NT treatments. High numbers of beneficial insects (Cotesia glomerata, Cotesia orobenae and Diadegma insulare) kept the primary insect pest population (Pieris rapae, Evergestis rimosalis (Guenee), and Plutella xylostella) at a pest to predator ratio below 4:1. Although the excellent insect pest control was attributed to the farmscape plantings, pest level and crop yields were not significantly affected by farmscaping (likely due to the close proximity of the farmscaped plots (10-50m from non-farmscaped)). Broccoli yield averaged 62% higher in fall than summer (12.1 vs. 7.5 t ha-1) likely due to cool weather conditions during broccoli head development (October), increasing head size, uniformity, and marketability. In 2004, broccoli yield in CT plots was either equal or slightly higher than NT (9.5 vs. 9.0 t ha-1). However, in 2005, broccoli yield in CT plots was significantly higher in both spring (8.8 vs. 6.8 t ha-1; p = 0.0258) and fall crops (13.5 vs. 12.3 t ha-1 with p = 0.0484). Nitrogen sidedressing improved yield in all plots (9.8. vs. 12.7 t ha-1) and particularly in NT (8.6 vs. 12.1 t ha-1), indicating that availability and/or synchrony of nitrogen was a limiting factor. Incorporating high-N legume residues in the grow zones resulted in a lesser N response in CT. / Master of Science

Phosphorus (P) is the second macronutrient that most limits the agricultural production due to its low level of availability in the soils, thus requires high demand to obtain high crops efficiency in the short-term, however, it is a non-renewable resource. In long-term, differents P fertilizer placement can effect, particularly the preferential forms of P retained and legacy in the soil pool and their contribution to increasing P use efficiency by crops over time. In this context, in the present thesis, in the chapter two, we aimed to assess changes in soil P pools (labile, moderately labile and non-labile) and legacy soil P accumulation after long-term P fertilization with an initial soil P buildup and annual P applications. P pools in the soil showed a significant effect of P application on labile P fractions with the adoption of annual rates of 60, 90 and 120 kg P2O5 ha-1, while effects of the initial P application were less significant for this tropical high weathered soil. Thus, P accumulation from annual rates in the labile fractions of P could help to improve the soil legacy P availability and represent a profitable strategy to reduce large inputs of inorganic P fertilizer in tropical crop production systems. in the chapter three, we evaluated the influence of long-term P fertilizer placement on soil P pools and legacy soil P accumulation under a corn-soybean long-term rotation. Significant changes in soil P pools were observed by the long-term effect of P fertilizer placement. Broadcast P fertilizer placement increased the labile P and moderately labile P in the topsoil (0-7.5 cm), and had a greater P fertilizer use efficiency compared to deep band placement. The use of combined placement strategies will contribute to maintain the available P pools maximizing P fertilization efficiency in reduced tillage systems. in the chapter four, we evaluated the effects of long-term P fertilizer placement (initial placement and annual rates and placement of P) in the transition of pasture to double-crop of soybean and corn under no-till crop production on changes in the soil P pools and legacy soil P accumulation. Results of P pools in the soil showed a significant effect of P application on labile P fractions in soil surface with the adoption of annual rates and placement of 100B and 100SP kg P2O5 ha-1 under all initial P application, and 100B for the all others P fractions and soil depths, while effects of the initial P application were less significant for this tropical high weathered soil. Thus, P accumulation from the initial (P remains in the soil after five years) and annual P fertilizer application in the labile P pools could help (at least in part) to reduce current high dependency and large inputs of inorganic P fertilizer in tropical no-till systems. / O fósforo (P) é o segundo macronutriente que mais limita a produção agrícola devido seu baixo nível de disponibilidade nos solos, exigindo alta demanda para obter alta eficiência das culturas em curto-prazo, porém, é um recurso não renovável. Em longo-prazo, diferentes adições desse fertilizante podem afetar as formas e o legado do P no solo e sua contribuição para aumentar a eficiência do seu uso pelas culturas ao longo do tempo. Neste contexto, no capítulo dois, avaliamos as mudanças nos pools de P do solo (lábeis, moderadamente lábeis e não lábeis) e o acúmulo do legado do P no solo após a fertilização P a longo prazo com o aumento do P inicial do solo com o uso de doses iniciais de P e aplicações anuais de P. As frações de P do solo mostraram um efeito significativo à aplicação de P nas frações lábeis de P com a adoção das doses anuais de 60, 90 e 120 kg de P2O5 ha-1 , enquanto os efeitos da aplicação inicial de P foram menos significativas para este solo tropical altamente intemperizado. Assim, o acúmulo de P nas frações lábeis promovidas pelas doses anuais de P poderia ajudar a melhorar a disponibilidade e legado do P no solo e representar uma estratégia lucrativa para reduzir grandes entradas de fertilizantes fosfatados inorgânicos nesses sistemas tropicais de cultivo. no capítulo três, avaliou-se a influência da adubação fosfatada a longo-prazo nas frações e legado do P do solo, sob rotação milho-soja. Foram observadas mudanças significativas nas frações de P do solo pelo efeito da aplicação de fertilizantes fosfatados em longo-prazo. A colocação do fertilizante fosfatado a lanço aumentou o P lábil e moderadamente lábil na camada superficial do solo (0-7,5 cm) e teve maior eficiência de uso deste fertilizante em comparação à apliacação profunda. O uso de estratégias de aplicações combinadas contribuirá para manter as fraçães de P disponíveis maximizando a eficiência da fertilização fosfatada nos sistemas de cultivo reduzido. no capítulo quatro, avaliamos os efeitos da adubação fosfatada a longo-prazo (aplicação inicial e doses e aplicações anuais de P), na transição do pasto para cultivo de soja e milho safrinha sob plantio direto, nas mudanças e acumulação das frações e legado do P no solo. As frações de P no solo mostraram um efeito significativo à aplicação de P nas frações lábeis na superfície do solo com a adoção das doses e aplicações anuais de 100B e 100SP kg P2O5 ha-1 em todas as aplicações iniciais de P, e 100B para todas as outras frações de P e profundidades do solo, enquanto os efeitos da aplicação inicial de P foram menos significativos para este solo tropical altamente intemperizado. Assim, o acúmulo de P da aplicação inicial (efeito residual do P no solo após cinco anos) e as aplicações anuais do fertilizante fosfatado nas frações de P lábil podem ajudar (pelo menos em parte) a reduzir a alta dependência atual às grandes entradas de fertilizante fosfatos inorgânico nos sistema de plantio direto.

Thesis (PhD(Agric) (Agronomy))--Stellenbosch University, 2008. / The adoption of the no-till planting method brought about changes to the way the wheat crop is established in the Mediterranean climate of the Western Cape. Row widths have to increase from the normal narrow rows (170-180 mm) to at least 250 mm to allow for sufficient stubble handling. Furthermore, planters are designed to place seed accurately in the soil at uniform depth, which may increase seedling survival rates. The main objective of this study was to determine the influence of the use of wide row widths on yield, the components of yield and grain quality parameters and to revisit planting density recommendations to be used with the notill planting method. On-farm, producer managed trials which included cultivars, row widths and planting density treatments were planted at Riversdale, Swellendam and Caledon in the Southern Cape region and at Moorreesburg and Hopefield in the Swartland during the 2004 to 2006 production seasons. All trials were factorial RCB designs with split-split plot arrangements. Grain yield, grain protein, hectolitre mass (HLM) and the yield components, seedlings m-2, seedling survival (%), number of heads m-2, number of heads plant-1, number of kernels head-1 and thousand kernel mass (TKM) were determined at all sites in 2005 and 2006. Seedling survival rates of 80% were easily achieved in all trials with the exception of Caledon and Swellendam in 2005. The no-till planting method may be efficient to improve on survival rates of 50-70% found with the conventional planting methods. The yield component response that raised the most concern was the clear trend of the reduction in the number of heads m-2 as row widths increased, which was significant in eight out of the nine experiments. The number of heads plant-1 decreased significantly as planting density increased in all experiments. Cultivars differed in the grain quality parameters grain protein (%) and HLM but were influenced minimally by the other treatments. Reductions in grain yield occurred in three out of eight trials in the Southern Cape and in three out of six trials in the Swartland, with reductions of between 6.8% and 33% in some seasons. The risk of yield loss due to wide row widths could not be excluded by this study and therefore the row widths used by producers should remain as narrow as practically possible. Grain yield response to increasing planting density differed between the two regions. No significant yield benefits were found in any of these trials if planting densities were increased above 175 target plants m-2. Planting densities may be reduced to between 70 and 87.5 kg seed ha-1 to achieve this target if the crop is planted in time and seedling survival rates of at least 80% can be achieved.

Magistrantūros studijų baigiamajame darbe pateikiami dirvožemio organinės anglies, humuso, C/N santykio, mikroorganizmų biomasės anglies, dirvožemio kvėpavimo tyrimų duomenys, įvertinant skirtingus žemės dirbimo būdus skirtingais dirvožemio gylio sluoksniais. Lyginami 2009 ir 2013 metų atliktų tyrimų duomenys. Darbo objektas – giliau karbonatingas giliau glėjiškas rudžemis, kuriame 2009 ir 2013 metais buvo žirnių (Pisum sativum L.) pasėlis, kur tirta skirtingo žemės dirbimo įtaka dirvožemio organinės anglies ir mikroorganizmų biomasės anglies sankaupoms. Darbo metodai: eksperimentai įrengti keturiais pakartojimais. Pradinių laukelių plotas – 126 m2, apskaitinių – 84 m2. Variantai pakartojimų blokuose išdėstyti rendomizuotai. Dirvožemio kvėpavimas ir mikroorganizmų biomasės sankaupos įvertintos 2009 ir 2013 m. birželio mėn. žirnių pasėliuose. Dirvožemio organinės anglies ir mikroorganizmų biomasės sankaupoms vertinti viršutinio ariamojo Ap (0-10 cm) horizonto jungtiniai ėminiai 3 pakartojimais buvo surinkti su 2-4 cm skersmens dirvožemio grąžtu. Eksperimento variantai: tradicinis žemės dirbimas, supaprastintas žemės dirbimas, tiesioginė sėja, ekologinė žemdirbystės sistema, kur taikytas tradicinis žemės dirbimas. Darbo rezultatai. Skirtingi žemės dirbimo būdai ir ekologinės žemdirbystės sistema, taikant tradicinį žemės dirbimo būdą, turėjo įtakos dirvožemio organinės anglies, humuso, C/N santykio, kvėpavimo ir mikroorganizmų biomasės anglies sankaupoms. Didžiausios org. C... [toliau žr. visą tekstą] / The master work presents the results on soil organic carbon, humus, C/N ration, microbial biomass carbon, soil respiration in soil with different soil tillage systems in two soil depths (0-10; 10-20 cm). Results were obtained in 2009 and 2013 and presented. Object of the research – The Endocalcari-Endohypogleyic Cambisol, where in 2009 and 2013 pea crops (Pisum sativum L.) have been growing. Soil tillage impact on soil organic carbon and microbial biomass carbon pools has been investigated. Method of the research – experiments was installed in four replications. Research area – 126 m2, research plot – 84 m2. Variants in blocks were rendomized. Soil respiration and microbial biomass pools were investigated in 2009 and 2013 in June in pea crops. Experiment variants were as followed: conventional tillage, reduced tillage, no tillage and ecological soil management with conventional tillage. Research results. Different soil tillage systems and ecological soil management system with conventional tillage had impact on soil organic carbon, humus, C/N ration, soil respiration and microbial biomass carbon pools. The highest org. C, humus, microbial biomass carbon concentrations and soil respiration intensity have been found in ecological soil management system. The fertilization with siderate crop may effect it mainly. The lower soil tillage intensity influenced the increase in org. C, humus concentration in 0-10 cm soil depth. In other hand, also along with lower tillage intensity... [to full text]

Tikslas – įvertinti tiesioginės sėjos, supaprastinto žemės dirbimo ir augalinių liekanų įtaką kai kuriems vasarinių rapsų agroekosistemos komponentams. Stacionarus dviejų veiksnių lauko eksperimentas įrengtas 1999 m. Aleksandro Stulginskio universiteto Bandymų stotyje. A veiksnys − šiaudų panaudojimas: šiaudai pašalinti (-Š); šiaudai susmulkinti ir paskleisti (+Š). B veiksnys − žemės dirbimos sistemos: įprastas gilus arimas 23–25 cm gyliu rudenį (GA), kontrolinis variantas; seklus arimas 10–12 cm gyliu rudenį (SA); seklus purenimas kultivatoriumi strėliniais noragėliais ir lėkštiniais padargais 8–10 cm gyliu rudenį (KL); seklus purenimas rotoriniu kultivatoriumi 5–6 cm gyliu prieš sėją (RK); seklus žaliosios trąšos įterpimas rotoriniu kultivatoriumi 5–6 cm gyliu prieš sėją (ŽTRK) ir tiesioginė sėja į neįdirbtą ražieną (ND). Vienoje bandymo dalyje šiaudai pašalinti, o kitoje dalyje susmulkinti ir paskleisti. Tiek fone be šiaudų, tiek fone su paskleistais šiaudais buvo tiriamos visos žemės dirbimo sistemos. Šiaudų įterpimas (+Š) neturėjo esminės įtakos tirtiems vasarinių rapsų agroekosistemos komponentams. Seklus purenimas rotoriniu kultivatoriumi 5–6 cm gyliu prieš sėją (RK) ir seklus žaliosios trąšos įterpimas rotoriniu kultivatoriumi 5–6 cm gyliu prieš sėją (ŽTRK) esmingai padidino vasarinių rapsų daigų skaičių. Dirvožemio kietį armenyje didino visos neariminio žemės dirbimo sistemos. Šlyties pasipriešinimą didino taip pat visos neariminio žemės dirbimo sistemos tiek 0–10 cm... [toliau žr. visą tekstą] / The aim of investigation – to evaluate effect of reduced soil tillage and plant residue on some rape agroecosystem components. Stationary two – factor field experiment was estab-lished in Aleksandras Stulginskis University at the Experimental station in 1999. Factor A – the use of straw: straw removed (-Š); straw chopped and spread (+Š). Factor B – tillage sys-tems: conventional deep ploughing at 23–25 cm depth in autumn (GA), control; shallow ploughing at 10–12 cm depth in autumn (SA); shallow loosening with tine coulter and disk implements at 8–10 cm depth in autumn (KL); shallow loosening with rotary cultivator at 5–6 cm depth before sowing (RK); shallow incorporation of green manure with rotary cultivator at 5–6 cm depth before sowing (ŽTRK) and no tillage, direct sowing (ND). In one field experiment part straw removed, and the other part chopped and spread. Both the background without straw and spread at the background of the straw was investigated all tillage systems. Straw incorporation (+Š) had no significant effect on studied rape agroecosystem components. Shallow loosening with rotary cultivator at 5–6 cm depth before sowing (RK) and shallow incorporation of green manure with rotary cultivator at 5–6 cm depth before sowing (ŽTRK) signitificantly increased the number of rape seedlings. All tillage systems in the soil plow layer increased the penetration resistence. All tillage systems significantly inc-reased shear strenght at 0–10 cm and 10–20 cm and depth. The... [to full text]

En agriculture de conservation (AC), les résidus de cultures sous forme de paillis à la surface du sol associés à la suppression du travail du sol sont une composante intrinsèque des systèmes de culture. L'objectif principal de ce travail était de comprendre les effets de la nature et de la décomposition de mulch de résidus s sur les services d'approvisionnement et de régulation fournis par les sols dans les agrosystèmes en AC de régions tempérées (France) et tropicales (Madagascar et le Brésil). Des études expérimentales ont été réalisées pour obtenir des paramètres de décomposition pour une large gamme représentative de la qualité des résidus végétaux des agrosystèmes étudiés et pour tester et améliorer un modèle de décomposition des mulchs. Ensuite nous avons utilisé le modèle PASTIS_MULCH qui simule les biotransformations C et N et le transport de solutés dans les sols lors de la décomposition des mulchs.Pour la gamme de résidus de tiges testées, la rétention d'eau maximale a varié considérablement et ceci a été expliqué par les caractéristiques physiques du résidu. Avec les données obtenues par une série d'incubations de décomposition de résidus, nous avons proposé un ensemble de paramètres biologiques unique pour le module de décomposition CANTIS, simulant une large gamme de qualité des résidus de culture. L'étude expérimentale dans les colonnes de sol a montré que le mulch de maïs + dolique se décompose plus rapidement que mulch de blé + luzerne. Un régime de pluies fines et fréquentes augmente la décomposition du mulch par rapport à des pluies plus rares et plus fortes et cela est dû au maintien de l'humidité du mulch.Les simulations de scénarios avec PASTIS_MULCH ont montré que la pluie et les conditions d'évaporation classent les résidus de culture vis-à-vis de la décomposition lorsque ceux-ci sont placés en mulch à la surface des sols, tandis que les caractéristiques chimiques des résidus classent ceux-ci vis-à-vis de la décomposition lorsqu'ils sont incorporés. Aucune des situations étudiées pourrait être définie au vu des résultats de simulation comme étant adaptée à toutes les conditions pédo-climatiques et agricoles. / In conservation agriculture (CA), crop residues mulches are associated to reduction or suppression of soil tillage and are an intrinsic component of CA. The objective of this work was to understand the effects of nature and decomposition of crop residue mulches on the provisioning and regulating services of agrosystems provided by soils under temperate (France) and tropical (Madagascar and Brazil) conditions. Experimental studies were realized to get decomposition parameters for a large range of residue quality representative of the agrosystems studied and to test and improve a MULCH model. Then we used PASTIS_MULCH model which simulates the C and N biotransformations and solutes transport in soils during mulch decomposition.For a range of plant-stem residues tested, the maximal water retention varied greatly and was only explained by the physical features of the residue. With a series of decomposition incubations, we proposed a single set of biological parameters for CANTIS decomposition module, simulating a large range of crop residue quality. Experimental study in soil columns showed that maize+dolichos mulch decomposed faster than wheat+alfalfa mulch. Frequent and light rain enhanced mulch decomposition compared to infrequent and heavy rain and this was due to the mulch remaining wetter with frequent rain.The simulations of scenarios with PASTIS showed that rain and evaporation conditions ranked crop residues decomposition when placed as mulches while the residue chemical characteristics ranked crop residues decomposition when incorporated. None of the situations studied would be defined as suitable in all pedo-climatic and agricultural conditions.

A pesquisa teve como objetivo verificar o fluxo de emergência das plantas daninhas e determinar o banco de sementes em condições de semeadura direta e convencional e verificar a eficácia do glyphosate em plantas daninhas de difícil controle. Para tanto, foi realizado no período de 2001 e 2002, um experimento de campo, onde de 15 em 15 dias, foi feito o levantamento de plantas daninhas para determinação do fluxo de emergência. O delineamento experimental foi o de blocos casualizados, com parcelas subdivididas. As doses de glyphosate foram de 0, 540, 720, 900, 1080, 1260 e 1440 g.i.a / ha. O banco de sementes foi avaliado através da retirada de 20 sub-amostras de solo, em cada parcela, nas profundidades de 0,0-2,5; 2,5-5,0; 5,0-10,0; 10,0-15,0 e 15,0-20,0 cm. Também foram realizados dois experimentos em câmara de crescimento com o objetivo de avaliar o controle e curvas dose - resposta das espécies de plantas daninhas Bidens pilosa L., Commelina benghalensis L., Digitaria insularis L. (Feed), Tridax procumbens L. e Ipomoea grandifolia Dammer e Spermacoce latifolia Abul. ao herbicida glyphosate. Para avaliar o controle, foram aplicadas as seguintes doses de glyphosate: 0, 720, 960; 1200, 1440, 1680, 1920 g.i.a/ha, após 25 dias da emergência das plantas daninhas. Na determinação das curvas-dose resposta as aplicações das doses de glyphosate foram de 0,0; 11,3; 22,5; 45; 90; 180; 360; 720 e 1440 g.i.a. / ha. A elaboração da curva dose - resposta foi feita através do ajuste da biomassa verde utilizando modelo matemático log-logístico: Y = C+D-C / 1 + Exp(b(log(x)-log(GR50))), calculado por modelo não linear dos dados. Nas análises estatísticas foram utilizados os programas estatísticos SAS e SANEST para analisar a variância dos dados. Nas condições locais de campo em que foi realizado o experimento podemos concluir que o herbicida glyphosate mostrou-se ser eficaz no controle de plantas daninhas existentes na área a partir da dose de 540 g.i.a/ha. No ano de 2001 ocorreram fluxos das espécies Leucas martinicensis Jacq. e Richardia brasilensis Gomes de uma forma mais diferenciada no direto do que no convencional. Também as espécies Cenchrus echinatus L. e Digitaria insularis (Feed) L. apresentaram maior emergência no sistema direto do que no convencional. No ano de 2002 essas diferenças dos fluxos das espécies não foram tão expressivas como em 2001. As sementes concentraram-se nos 2,5-5,0 cm superficiais do solo, no sistema direto, enquanto que o preparo convencional distribuiu as sementes em maiores profundidades. Os resultados obtidos em câmara de crescimento indicaram que o herbicida glyphosate controlou Bidens pilosa e Digitaria insularis. Commelina benghalensis foi considerada de difícil controle. A dose de glyphosate necessária para atingir índices de controle acima de 91% foi de 1680 g.i.a/ha para Commelina benghalensis, 960 g.i.a/ha na espécie Tridax procumbens e 1440 g.i.a/ha aos 21 DAA para Ipomoea grandifolia. Após a determinação da curva dose - resposta concluiu-se que a espécie Bidens pilosa foi considerada a planta daninha mais suscetível ao herbicida glyphosate, pois foi a espécie que obteve menor GR50 (31,86 g.i.a/ha). As espécies Tridax procumbens, Digitaria insularis, Spermacoce latifolia, Ipomoea grandifolia, Commelina benghalensis obtiveram GR50 de 58,40; 128,50; 250,44; 615,49 e >1440,00 g.i.a/ha, respectivamente. / The research had the objective of determining the emergence periodicity, seeds bank for the no tillage and convencional tillage systems, and verify the efficacy of glyphosate on weeds of difficult control. During 2001 and 2002, a field experiment was conducted where after applications of glyphosate in the no tillage and convencional tillage systems was made every 15 days the emergence periodicity and seeds bank determination. The experimental design was the randomized blocks with subdivide plots. The applied glyphosate rates were 0, 540, 720, 900, 1080, 1260 and 1440 g.i.a.ha -1 . The bank of seeds was evaluated through the retreatment of 20 soil sub-samples, in each plot, in the depths of 0.0-2.5; 2.5-5.0; 5.0- 10.0; 10.0-15.0 and 15.0-20.0 cm. Experiments were also led in a completely randomized black growth chamber with the objective of evaluating the susceptibility and dose-response curves of the species of weeds Bidens pilosa L., Commelina benghalensis L., Digitaria insularis L. (Feed), Ipomoea grandiofolia L., Tridax procumbens L. and Spermacoce latifolia Abul. to the herbicide glyphosate. To evaluate the control the following glyphosate doses: 0, 720, 960; 1200, 1440, 1680, 1920 g.i.a.ha -1 . The applications of glyphosate were doses of 0, 11.3, 22.5, 45, 90,180, 360, 720, and 1440 and g.i.a.ha -1 . The elaboration of the curves dose - response was made through the adjustment of the green biomass it dries using the following mathematical model log - logistic: Y = C+D-C / 1 + Exp(b(log(x)-log( GR50))), using the statistical procedure of non linear analyses. The SANEST program was used to the statistical analyses and SAS program to analyze the variance of the data. In field conditions of field were experiment was carried out, glyphosate was effective to control of weeds starting from dose of 540 g.i.a.ha -1 . In the year of 2001, emergence periodicity of the species dicotiledons Leucas martinensis Jacq. and Richardia brasilensis Gomes in a more different way in the no tillage than in the convencional tillage; also, the species monocotiledons Cenchrus echinatus L. and Digitaria insularis L. (Feed) presented a larger emergence in the no tillage than in the convencional tillage systems. In the year of 2002, that differences of the flows of the species were not as expressive as in 2001. The seeds concentrated on the 2.5-5.0 cm superficial of the soil, in the no tillage system, while the convencional tillage distributed the seeds in the soil. The results in the chamber showed that glyphosate controlled Bidens pilosa and Digitaria insularis. Commelina benghalensis was considered a specie of difficult control. The glyphosate rate to reach control indexes above 91% was of 1680 g.i.a.ha -1 of glyphosate for Commelina benghalensis, 960 g.i.a.ha -1 in the Tridax procumbens and 1440 g.i.a.ha -1 of glyphosate for Ipomoea grandifolia in 21 DAA. After the curves dose - response determination it was ended that Bidens pilosa was considered the more susceptible weed to glyphosate, because it was the species of smaller GR50 (31.86 g.i.a.ha -1 ). On the other hard species Tridax procumbens, Digitaria insularis, Spermacoce latifolia, Ipomoea grandifolia, Commelina benghalensis obtained GR50 equal to 58.40, 128.50, 250.44, 615.49 and >1440,00 g.i.a.ha -1 , respectively.