Baby corn (Zea mays L.) consists of unfertilized young ears harvested at silkemergence. The 2011 study was a culmination of four successive years of productionand evaluation of baby corn at Western Kentucky University (36.93 N, 86.47 W). Theobjective was to compare the effect of tassel removal on baby corn (BC) production onfour cultivars of corn, two field (‘N77P-3000GT’, ‘N68B-3000GT’) and two sweet(‘Silver Queen’, ‘Peaches N Cream’). Results indicated that tassel removal gavesignificant increases (P<0.01) of BC ears across harvests (H) and cultivars; however, the effect was not consistent over treatments. For harvests, the difference due to detasseling was significant (P<0.05) for H2 and H3, but not significant (P>0.05) for H1 or H4. For cultivars, numerical values were higher for detasseled than non-detasseled treatments in the first three harvests for each cultivar, but significant (P<0.05) only for ‘Peaches n’ Cream’. Quality of BC from both tassel treatments decreased in H3 and H4. Based upon the increased number of ears resulting from detasseling, additional labor costs would be more than covered. Baby corn has excellent potential as a niche crop for producers and consumers in Central Kentucky.

<p>Savremena poljoprivredana proizvodnja mora da odgovori na sve veće zahteve u pogledu za&scaron;tite životne sredine, smanjenja tro&scaron;kova proizvodnje i rasta tražnje za visoko kvalitetnim i zdravstveno bezbednim proizvodima. U takvim uslovima, jedan od odgovora poljoprivrednih proizvođača na postavljene izazove je i gajenje ozimih međuuseva jer oni mogu pružiti različite ekolo&scaron;ke i proizvodne prednosti u poljoprivrednoj proizvodnji. Zbog toga, cilj rada je ispitati koje biljne vrste se mogu gajiti kao ozimi međuusevi u na&scaron;im agroekolo&scaron;kim uslovima, kakav je njihov uticaj na zemlji&scaron;te, kakve su prednosti njihove primene za stočnu hranu ili za zeleni&scaron;no đubrenje i kakav im je uticaj na sledeći usev. Ogled je postavljen na tri lokaliteta po metodi slučajnog blok sistema u tri ponavljanja. Istraživanja su izvr&scaron;ena u dva proizvodna ciklusa, od oktobra 2011. godine, kada su posejani ozimi međuusevi, do septembra 2013. kada je poko&scaron;en kukuruz za silažu. Biljne vrste kori&scaron;ćene za ozime međuuseve su maljava grahorica (Vicia vilosa Roth., sorta NS-Sirmium), ozimi tritikale (x Triticosecale Wittm. ex A. Camus, sorta Odisej) i njihova sme&scaron;a. Pored varijanti sa ozimim međuusevima u ogled su uključene i varijante sa đubrenjem mineralnim azotom prema N-min metodi do 120 kg/ha azota (N1) i do 160 kg/ha azota (N2), kao i kontrola. Ozimi međuusevi posejani u prvom bloku su kori&scaron;ćeni za krmu, dok su međuusevi posejani u drugom bloku zaorani. U zavisnosti od vremenskih uslova ispitivane biljne vrste i njihove sme&scaron;e gajene kao ozimi međuusevi, mogu da ostvare visoke prinose. Njihovim zaoravanjem značajno se može popraviti sadržaj mineralnog azota u zemlji&scaron;tu i obezbediti značajno povećanje proizvodnje kabaste stočne hrane na gazdinstvima. Dinamika mineralnog azota u zemlji&scaron;tu visoko je zavisna od ozimih međuuseva i najniži sadržaj azota je posle njihove žetve. Od ispitivanih vrsta, najvi&scaron;u količinu azota iznosi tritikale, zatim ozima krmna sme&scaron;a, a najmanje ozima grahorica. Od setve do žetve silažnog kukuruza, sadržaj mineralnog azota u zemlji&scaron;tu se povećava na svim tretmanima. Sadržaj mineralnog azota na kraju vegetacije je vi&scaron;i na tretmanima gde je zelena masa međuuseva odneta sa parcele. Međutim, preostala<br />količina azota (ARNS) posle žetve kukuruza statistički je značajno vi&scaron;a na tretmanima gde su zaorani ozimi međuusevi od tretmana gde su oni odneti sa parcele i kreće se u intervalu od 66 do 150 kg N ha-1, a najveća je posle ozime krmne sme&scaron;e. Prinosi zelene mase kukuruza u naknadnoj setvi posle ozimih međuuseva niži su u odnosu na varijante sa đubrenjem i kontrolu i kreću se od 6,6 t ha-1 do 22 t ha-1, dok kvalitet silokrme zadovoljava energetski potencijal kao i sadržaj proteina i minerala za kvalitetnu ishranu stoke na gazdinstvima. Datum</p> / <p>A modern agricultural production must respond to increasing demands in terms of environmental protection, reduction of production costs and an increased demand for high quality, safe and healthy products. In such conditions, one of the responses of agricultural producers to the challenges posed is also cultivation of winter cover crops, because they can provide different advantages in agricultural production in terms of ecology and production. Therefore, the aim of the research is to examine which plant species can be cultivated as winter cover crops in our agroecological conditions, their impact on the soil, the benefits of their application as animal feed or green fertilizer, and the impact they have on the subsequent crop. The field experiment was conducted on three locations using the&nbsp; random block design with replications. The research was carried out in two production cycles, from October 2011, when the winter cover crops were sown, to September 2013, when corn was reaped for silage. Herbaceous species used for winter cover crops are hairy vetch (Vicia vilosa Roth., variety NS-Sirmium), winter triticale (x Triticosecale Wittm. Ex A. Camus, Odyssey variety) and their mixture. In addition to variants with winter cover crops, variants with fertilization with mineral nitrogen according to the N-min method up to 120 kg/ha of nitrogen (N1) and up to 160 kg/ha of nitrogen (N2), as well as a control, are included in the field experiment. Winter cover crops sown in the first block were used for fodder, while the winter cover crops sown in the second block were ploughed. Depending on&nbsp; weather conditions of the tested plant species and their mixture grown as winter cover crops, they can achieve high yields. Their ploughing can significantly improve the content of mineral nitrogen in soil and provide a significant increase in voluminous fodder production in farms. The dynamics of mineral nitrogen in soil is highly dependent on winter cover crops and the nitrogen content is the lowest after their harvest. Out of the tested species, the highest&nbsp; nitrogen uptake was by triticale, then winter forage mix and the smallest by winter vetch. In the period from sowing to harvest of silage corn, the<br />content of mineral nitrogen in soil increases with all treatments. The content of mineral nitrogen at the end of the vegetation is higher with treatments where the green mass of the cover crops were taken away from the plot. However, the remaining quantity of nitrogen (ARNS) after corn harvest was, statistically speaking, significantly higher in treatments where winter cover crops were ploughed, from the treatment where they were taken away from the plot and ranges from 66 to 150 kg N ha-1; the largest nitrogen content was measured after winter forage mix. The green mass yields of corn in subsequent sowing after winter cover crops are lower compared to fertilized variants and the control and range from 6.6 t ha-1 to 22 t ha-1, while the quality of silage meets the energy potential, as well as the content of proteins and minerals for quality livestock feed on farms.</p>

Thesis (M.Sc. (Soil Science)) --University of Limpopo, 2013 / Large amount of pre-plant nitrogen (N) fertilizer results in low nutrient-use-efficiency due to poor synchrony between soil N supply and maize demand, especially during N sensitive growth stages. Optimum maize production is dependent on adequate N availability to the crop during the critical vegetative and reproductive growth stages. High N fertilizer prices and maize yield decline are the main challenges faced by the Limpopo Province farmers. The objectives of this study were to compare growth and yield of maize under conventional and site-specific N management in a dryland farming system. The study was conducted in Leeukraal, Towoomba, Ga-Marishane and Radium in the Limpopo Province, South Africa. Experimental plots were laid out in a randomized complete block design, with four replications. Phosphorus was applied through band placement using a planter in all plots at a rate of 42 kg P/ha. Hybrid maize SNK 2147 was planted on a 20 by 20 m plot with Inter-row and Intra-row spacing of 0.9 and 0.35 m respectively. Treatments consisted of 3 N management strategies as follows, (i) No N application (N0), (ii) Site-specific N at a rate ranging between 18 and 33 kg N/ha (N1) and (iii) Conventional N application at 58 kg N/ha (N2). Treatment N2 was applied at a uniform rate during maize planting. Sufficiency index as an indication for N deficiency was determined using CCM-200 for treatment N1. The sufficiency index was determined during leaf stage V6, V10 and V14, and thereafter N was applied only when needed. Data were subjected to analysis of variance through Statistical Analysis System package. Mean separation tests were computed using Duncan’s Multiple Range Test. Maize grain yield at Leeukraal of 5.2 t/ha for N1 was higher than 3.2 and 4.0 t/ha of N0 and N2, respectively. There was no difference amongst the three N management approaches on the grain yield at Towoomba. The grain yield at Ga-Marishane for N1 of 2.2 t/ha was significantly higher than 1.7 t/ha of the N0. Conventional management approach, which is a traditional approach used by farmers in the Limpopo Province, had 2.6 t/ha grain yield that was significantly higher than the N0 and N1. The maize growth and yield under N2 and N1 was compared, N1 required between 43 and 69% lesser N fertilizer as compared to N2. Therefore site-specific nutrient management approach sustains and improves growth and yield of maize using minimal inputs of N compared to conventional approach. This therefore saves input costs and avoids unnecessary environmental consequences. Key words: maize yield, nitrogen management, site-specific approach / Vlaamse Interuniveritatire Raad and Limpopo Department of Agriculture

Land application of biosolid or industrial compost raises concerns regarding heavy metal accumulation in soils, plants and free-ranging livestock. A strip-split plot design evaluated two levels of sewage sludge (22/44 t ha-1) and municipal solid waste (21/42 t ha-1) compared to nitrogen fertilizer and an unfertilized control. Treatments were evaluated with three levels of limestone (CaCO3 at 0, 3 and 6 t ha-1) over two years corn seeded no-till. Swiss Chard cultivated in field soil samples within a greenhouse monitored heavy metal bioavailability. Compost amended soil was incorporated into chicken feed to simulate soil ingestion in a free-range production system. Compost application increased total soil Pb over time yet decreased both available soil and corn plant Cu levels over time. No heavy metal accumulation was observed in Swiss Chard or poultry tissue. Biosolid composts containing elevated Cu or Pb levels can be safely used for crop or free-range broiler production.

Employing the causal inference methods (matching for binary and continuous treatments), I examined the impact of conservation payments on corn yield. I used the propensity score and covariate distance matching and generalized propensity score methods to manage the problem of selection bias since the enrollment of conservation programs (i.e., receiving conservation payments) is not a randomized experiment. Using USDA Economic Research Service – Agricultural Resource Management Survey (ERS-ARMS) field-level data, I assessed whether receiving conservation payments had harm on corn yield in the Mississippi and Arkansas Delta. The findings from the two binary matchings showed that receiving conservation payments didn’t decrease corn yield. The generalized propensity approach revealed that lower conservation payments received held higher corn yield while higher conservation payments led to lower corn yield.

Cover crops are widely planted in the mid-Atlantic region for their environmental and agronomic benefits, but incomplete or delayed termination can lead to cover crops becoming weeds in the subsequent cash crop, known as volunteers. Studies were conducted from 2020-2022 to evaluate the effect of four commonly grown cover crop species, winter wheat (Triticum aestivum L.), cereal rye (Secale cereal L.), hairy vetch (Vicia villosa Roth), and rapeseed (Brassica napus L.), and four termination timings; 28, 14, 5, and 1 days before corn planting (DBP). Results indicated volunteerism was only an issue with rapeseed. Delaying rapeseed termination resulted in 0, 5, 12, and 22 volunteer plants m-2 at 28, 14, 5, and 1 DBP in corn. In order to manage these rapeseed volunteers, herbicide evaluations were conducted and indicated that atrazine, isoxaflutole, metribuzin, and pyroxasulfone resulted in 92-94% control when applied preemergence. Similarly, atrazine and glyphosate provided 99% rapeseed control and glufosinate resulted in 89% control when applied postemergence. Therefore, volunteers can easily be controlled with commonly used herbicides in corn. Studies were also conducted to evaluate the benefits of these cover crops, which have the potential to overcome the aforementioned risks. Results indicate that hairy vetch produced the most biomass and provided greater control of summer annual grasses, small-seeded broadleaf and large-seeded broadleaf weeds than other cover crops. Biomass accumulation and extent of weed control increased with delaying cover crop termination. Corn yield was greatest following hairy vetch and was least in rapeseed plots. Termination of cover crops 14 DBP planting increased corn yield by 12%; whereas termination at 1 DBP decreased corn yield by 15% as compared to no cover crop-no till plots. Effective termination of cover crops is an important management consideration and information on termination efficiency can help in devising management plans. In order to assist managers by evaluating cover crop termination efficiency, studies were conducted to evaluate selective and non-selective herbicides and a roller crimper for correlating vegetative indices with visible termination efficiency. Among vegetative indices, the Green Leaf Index had the highest Pearson correlation coefficient for wheat (r = -0.79, p = <0.0001) and cereal rye (r = -0.80, p = <0.0001) with visible termination efficiency. Whereas, for rapeseed, Normalized Difference Vegetation Index (NDVI) had the highest correlation coefficient (r = -0.66, p = <0.0001). However, for hairy vetch none of the vegetative indices correlated significantly with visible termination efficiency. While further research is necessary, remote sensing technologies may help in devising management plans by increasing crop scouting efficiency. / Master of Science in Life Sciences / Cover crops reduce soil erosion, leaching of soil nutrients in the water bodies, and provide benefits like weed suppression and improving the cash crop yield. Cover crops are generally planted in fall after the harvest of cash crop and are killed (terminated) before or after planting of next cash crop in the spring. Cover crop plants can also become weedy when they grow as volunteer plants in cash crops and if not terminated effectively. Therefore, effective termination of cover crops is also an important management consideration. Keeping these aspects in view, field experiments were conducted to evaluate different cover crops, winter wheat, cereal rye, hairy vetch, and rapeseed and four termination timings, 28, 14, 5, and 1 days before corn planting (DBP) for biomass accumulation, weed control, and impact on corn yield. Among cover crops, hairy vetch was found to be the best in terms of biomass production, weed control, and improving corn yield, whereas rapeseed had least biomass accumulation and reduced corn yield. Among termination timing, 1 and 5 DBP resulted in the most biomass production and weed control, but corn yield was greatest when terminated at 14 DBP. Delaying rapeseed termination from 28 DBP to 14, 5, and 1 DBP increased volunteer rapeseed in corn by 5, 12, and 22 plants m-2. Preemergence (PRE) and postemergence (POST) herbicides were evaluated for volunteer rapeseed control in corn. Among preemergence (PRE) herbicides, mesotrione, rimsulfuron and flumioxazin provided more than 95% volunteer rapeseed control, whereas atrazine, isoxaflutole, metribuzin, and pyroxasulfone provided 92-94% control. Among postemergence (POST) herbicides, atrazine and glyphosate provided 99% visible control of rapeseed, followed by glufosinate (89%). Various selective and non-selective herbicides were also evaluated for the termination of wheat, cereal rye, hairy vetch, and rapeseed. Non-selective herbicides like glyphosate, glufosinate and paraquat were found more effective for termination of cover crops as compared to non-selective herbicides. Vegetative indices (VI) were evaluated and correlated with visible termination efficiency (ground truth data) and found that VI can be used for estimating termination efficiency and these estimates can help in devising plans for management operations. Among VI, Green Leaf Index had the highest correlation coefficient for wheat and cereal rye visible termination ratings. Whereas for rapeseed, Normalized Difference Vegetation Index (NDVI) had the highest correlation coefficient value. However, for hairy vetch none of the vegetative indices correlated significantly with visible termination efficiency. Overall, hairy vetch was found to be the best cover crop for biomass accumulation, weed control and corn yield improvement. Delayed termination of rapeseed plants resulted in infestation of volunteer rapeseed in corn and reduced corn yield. However, volunteer rapeseed plants can be effectively managed by effective termination and use of proper PRE and POST herbicides in corn. Furthermore, remote sensing-based VIs have shown potential to estimate cover crop termination efficiency.

<p dir="ltr">In response to fluctuating corn (<i>Zea mays</i> L.) prices, climatic variability, and emerging diseases, farmers are increasingly adopting diverse and intensive management practices to enhance yield and profitability. This research investigates the performance of various inputs and management practices on corn production across multiple site-years, with a focus on yield components, grain fill duration, kernel development, disease severity, and economic outcomes. A multi-state research trial was established to evaluate the impact of seven inputs and management practices across multiple locations and environments in Indiana, Kentucky, and Michigan in 2022 and 2023. Each location included eight treatments: 1) control treatment (C) based on Purdue University seed rate and nitrogen (N) fertilizer recommendations (Camberato et al., 2022; Nielsen et al., 2022): 30K seeds per acre and N fertilizer application as starter (2x2) and V5 growth stage sidedress. Total N rates ranged between 180 and 200 lbs N per acre and agronomic optimum nitrogen rates (AONR) were used, 2) C + banded (2x2) fungicide, 3) C + 20% increase in corn seeding rate, 4) C + sulfur (S) fertilizer, 5) C + foliar micronutrients, 6) C + late-season N fertilizer application (V10-12 growth stage), 7) C + R1 foliar fungicide, and 8) intensive treatment (all additional inputs/management practices applied). The intensive treatment significantly increased yield by 16.4 and 18.4 bu ac^-1 in 2022 and 2023, respectively when compared to the control across locations, but did not enhance net profit across multiple corn price scenarios due to high application costs. Conversely, R1 fungicide applications increased yield by 16.2 and 16.7 bu ac^-1 in 2022 and 2023, respectively, and S applications increased yield by 12.9 bu ac^-1 in 2023, when compared to the control, with both treatments improving net profit under multiple corn price scenarios. In addition, kernel development studies in West Lafayette, IN, during 2022 and 2023 revealed that banded fungicide applications at planting and foliar fungicide applications at the R1 growth stage can reduce leaf disease severity by 3.2% to 6.6%, extend grain fill duration by 3.5 to 4.5 days, and increase maximum dry kernel weight at plant maturity by 5.7 to 9.4%, respectively, leading to further insights into the yield response mechanisms. Furthermore, a meta-analysis of 24 at-plant flutriafol fungicide placement trials across Indiana (2020 – 2023) highlighted the effectiveness of at-plant fungicides, with banded (2x2 or 2x0) applications leading to the highest yield increase of 7.8 bu ac^-1 and both banded and in-furrow applications reducing disease severity on corn ear leaves at the R5 growth stage by 2.1 - 2.3% when compared to the control. These findings suggest both at-plant banded and R1 foliar fungicide applications have the potential to reduce disease severity, extend corn grain fill duration, and improve yield when conditions are conducive for a response (e.g., foliar disease presence). Overall, this research highlights the ability of targeted input applications for improving both corn yield and profitability when examined across diverse environments and locations, rather than prophylactic applications of multiple inputs and increased management intensities.</p>

<p></p><p>It is estimated that in the United States, agronomic weeds are responsible for about 50% of crop yield loss, costing nearly $27 billion each year. As interest in cover crops across the Midwest increases, so does the need to understand when to terminate cover crops for maximum weed control while still maintaining crop yield. Field experiments were conducted in 2017 and 2018 in Indiana to evaluate the effect of cover crop termination timings on weed control, and corn and soybean yield. Cereal rye (<i>Secale cereale </i>L.) and canola (<i>Brassica napus </i>L.) were subjected to early- or late- termination utilizing glyphosate-, saflufenacil- or glufosinate-based burndown herbicide programs. In corn, cereal rye and canola reduced early season weed biomass by 58 to 67% compared to fallow (no cover crop) plots. Cereal rye and canola reduced horseweed (<i>Erigeron canadensis </i>L.) and giant ragweed (<i>Ambrosia trifida </i>L.) emergence by 42 to 50% compared to fallow plots. Early- and late- terminated cereal rye reduced corn yields by 55 to 67% (5,173 to 7,116 kg ha^-1) compared to canola or fallow plots. In soybean, cereal rye and canola reduced early season weed biomass by 73 to 88% compared to fallow plots. Cereal rye and canola reduced horseweed emergence in 2017 and 2018 by 16 to 67 % compared to fallow plots. In 2017, both cover crop and termination timing influenced giant ragweed emergence. Early- and late- terminated cover crop plots reduced giant ragweed emergence by 50 to 76% compared to fallow plots. In 2018, cover crop termination timing influenced soybean yield. Late-terminated plots reduced yields by 48% compared to early-terminated plots. Results from this study suggest that cereal rye and canola planted at these rates can be effective for weed suppression prior to corn and soybeans, however, yield loss in both corn and soybean is expected. </p><p>Reports from Indiana in 2015 suggested that growers planting canola as a cover crop were experiencing difficulties when terminating with glyphosate prior to corn and soybean production. This suggests the utilization of inadequate herbicide programs, or perhaps a seed contamination event containing glyphosate resistant canola. Field experiments were conducted in 2016 and 2017 to determine the most effective herbicide treatment for terminating glyphosate resistant canola in Indiana, and to quantify how these herbicide programs influence corn yield. Canola was planted in early September and herbicide treatments were applied in the spring three weeks before corn planting. Visual ratings of control and above-ground biomass reduction were collected 21 days after treatment (DAT). The highest control of canola occurred following the application of paraquat + saflufenacil + 2,4-D or metribuzin, resulting in 88 to 94% control. These control ratings are supported by applications with paraquat + saflufenacil + 2,4-D or metribuzin resulting in 88 to 97% biomass reduction. Auxin herbicides alone provided very poor control, less than 41% at both locations. In general, saflufenacil-containing herbicide treatments provided the highest control of canola compared to mesotrione or atrazine. Herbicide treatments had no effect on corn grain yield.</p><br><p></p>

Agricultural intensification reliant on monocrops could change soil health in a way that does not support maximum crop productivity. Twenty-nine-year-old no-till field plots at the University of Kentucky Spindletop research farm showed a significant reduction in corn yields from continuous corn plots compared to those from plots in various types of rotation. The objective of this study was to determine what role soil microbes might play in yield reduction and how management and time effects microbial community structure. Samples were collected from the following treatments: continuous corn (CC), continuous soybean (SS), a 2-year corn/soybean rotation (CCSS), Corn in rotation with soybean with winter wheat cover (C/W/S), and sod controls (SOD). Soil health-related parameters were determined along with microbial community structure using phospholipid fatty acid analysis (PLFA). Results show that there is a strong seasonal dynamic in microbial communities with May, July and September showing the greatest differentiation between treatments. Nonparametric multidimensional analysis (NMDS) shows that microbial communities under SS, CC treatments were significantly different from the CS and CWS treatments across all four years of the study. My findings will prove useful for assessing the contribution of biological indicators to agroecosystem function and will aid in making recommendations of when and how to manage these parameters to improve soil health and maximize yield.

Made available in DSpace on 2017-07-25T19:30:46Z (GMT). No. of bitstreams: 1 Daniel Potma.pdf: 2269780 bytes, checksum: 5e498b4886f52a509f48ad0c44a512b3 (MD5) Previous issue date: 2014-07-23 / The total organic C (TOC) of the soil influences their chemical, physical and biological properties, therefore, it's important for the maintenance of soil fertility mainly of tropical soils. But, while the benefits of TOC accumulation on soil quality are well known, there is still little information about its effects on crop yields. The aims of this work were to map the compartments of the TOC on a farm managed for 30 years in no-till system, determine which soil variables that influence the spatial variation of TOC and analyze the relationships between the compartments of TOC and crop yields of soybean, corn and wheat. Deformed samples were collected in all soil classes and all landscape positions in the farm. Were analyzed the TOC, the permanganate oxidized C (POX-C) and the hot water extracted C (HWE-C) and were generated maps with the spatial variation of these variables. The effects of soil properties on the accumulation of TOC and the effect of TOC compartments on yields of soybean, corn and wheat were accessed through regressions and principal component analysis. Aiming to access the contribution of TOC to the crop yields, multiple regressions with the soil variables and yields were adjusted. The higher clay content and the largest biomass apport in Oxisols and the formation of an anaerobic environment in Inceptisols were the main factors that explained the highest contents of TOC observed in the upper thirds of the Oxisols and lower thirds of the Inceptisols. Yields of wheat and soybean showed positive correlation with TOC and total N (TN) and corn yield was positively correlated with HWE-C. The TN and TOC were the variables that contributed most to explain the variations in the wheat yield. / O C orgânico total (COT) do solo exerce influência sobre suas propriedades químicas, físicas e biológicas, sendo assim, importante para a manutenção da fertilidade principalmente de solos tropicais. Porém, embora os benefícios do acúmulo de COT sobre a qualidade do solo sejam bem conhecidos, ainda são escassas informações referentes aos seus efeitos sobre a produtividade de culturas. Os objetivos deste estudo foram mapear os compartimentos de COT em uma fazenda manejada há 30 anos no sistema plantio direto, verificar quais são as variáveis do solo que interferem na variação espacial do COT e analisar as relações entre os compartimentos do COT e a produtividade das culturas da soja, milho e trigo. Foram coletadas amostras deformadas em todas as principais classes de solos da fazenda em todas as posições da paisagem. Foram analisados o COT, o C oxidado por permanganato (C-OXP) e o C extraído por água quente (C-EAQ) e gerados mapas com a variação espacial destas variáveis. Os efeitos dos atributos do solo sobre o acúmulo de COT e dos compartimentos de COT sobre as produtividades da soja, milho e trigo foram acessados através de regressões e análises de componentes principais. Visando acessar a contribuição do COT para as produtividades das culturas foram ajustadas regressões múltiplas com as variáveis do solo e as produtividades. O maior conteúdo de argila e a maior adição de fitomassa nos Latossolos e a formação de um ambiente anaeróbico nos Cambissolos foram os principais fatores que explicaram os maiores conteúdos de COT observados nos terços superior dos Latossolos e inferior dos Cambissolos. As produtividades de trigo e soja apresentaram correlação positiva com o COT e o N total (NT) e a produtividade de milho apresentou correlação positiva com o C-EAQ. As variáveis NT e COT foram as que mais contribuíram para explicar a variação da produtividade de trigo.