Soybean (Glycine max [L.] Merr.) has become one of the main agricultural grain crops produced in the United States. Soybean production continues to increase in high-yield environments throughout the U.S. New innovations are required to sustain gains in soybean yield potential. Field experiments were conducted at the Delta Research and Extension Center in Stoneville, MS in 2014 and 2015 to evaluate soybean aboveground biomass and grain yield response to supplemental N fertilization in a high-yielding environment on two soil textures commonly cropped to soybean in Mississippi. Greenhouse studies were conducted in 2016 at the Delta Research and Extension Center in Stoneville, MS to evaluate the influence of supplemental N fertilization on nodule formation and belowground biomass of soybean on two soil textures commonly cropped to soybean in Mississippi.

No description available.

O nitrogênio (N) é o nutriente exigido em maior quantidade pelo cafeeiro e o segundo mais exportado pelos grãos. O uso do consórcio entre o cafeeiro e a braquiária é cada vez mais usado pelos cafeicultores. Nesse sistema de produção a fertilização é feita, em geral, nas duas espécies, sem conhecimento suficiente que respalde esse manejo. O N do resíduo vegetal pode ser absorvido pela planta após a mineralização, ser perdido por vários processos, ou ainda, ser imobilizado pela microbiota. O uso de fertilizantes enriquecidos isotopicamente é uma ferramenta que permite avaliar o N do fertilizante nos componentes do sistema, como no resíduo da forrageira, no solo e na planta. Essa pesquisa foi realizada com o objetivo de avaliar o crescimento e a produtividade do cafeeiro; elaborar o balanço de N; e avaliar a decomposição da biomassa da braquiária sob a copa do café, como fonte desse nutriente. A biomassa da braquiária sob a copa do cafeeiro reduziu em 49% a perda de água nos meses secos, com aumento do crescimento da planta entre março e setembro de 2011. A granação dos frutos e a produtividade do cafeeiro foram superiores quando aplicou-se 50% da dose do N na planta e os outros 50% na braquiária, cujo resíduo foi depositado sob a copa da planta, para a decomposição. A forrageira recuperou mais N (84,28% do aplicado ou 126,42 kg ha-1) do que o cafeeiro (38,63% ou 57,94 kg ha-1 de N), com a aplicação da mesma dose de N em ambas as plantas. O cafeeiro recuperou 38,63% do N do fertilizante, quando todo o N foi fornecido à planta; recuperou 14,31% do N (21,46 kg ha-1) na aplicação feita somente na forrageira, em que o resíduo foi depositado sob a copa da planta; e recuperou 53,3% do N (39,98 kg ha-1) do adubo e outros 15,28% (11,46 kg ha-1) proveniente da decomposição da biomassa, na aplicação da mesma dose de N na cultura e na forrageira. A taxa de crescimento do cafeeiro (altura e ramos produtivos) no período seco, de março a setembro de 2011, foi superior quando a planta e a forrageira receberam a mesma dose de N. A competição líquida por N entre a braquiária e o café foi pequena e variou de 1,22% (0,91 kg ha-1) a 0,24% (0,34 kg ha-1 de N), sem prejuízo ao crescimento e à produtividade do cafeeiro. A perda de N por lixiviação foi maior quando forneceu todo o N somente no cafeeiro (6,05% do N aplicado ou 9,07 kg ha-1), em relação à adubação feita apenas na braquiária (1,02% ou 1,53 kg ha-1 de N); e, na aplicação de doses iguais no café e na braquiária, a lixiviação variou de 3,4% do N aplicado (2,55 kg ha-1) sob a copa da planta a 1,15% (0,86 kg ha-1) na área da forrageira, cultivada na entre linha da cultura. A biomassa da braquiária fertilizada com N possuia menores relações lignina/N e C/N; e a mineralização do N foi mais rápida do que a decomposição da biomassa. A ciclagem do N depende da época de corte, com maior intensidade quando a ceifa ocorreu entre 30 e 55 dias na braquiária fertilizada e até 30 dias após rebrota, quando não recebeu N. / Nitrogen (N) is the nutrient required in larger quantities by coffee and the second most exported by the grains. The use of intercropping coffee and the Brachiaria is increasing within coffee farmers. In this production the fertilization is done generally in both species, without enough knowledge support for this. The N of the plant residue can be absorbed by the plant after mineralization, can be lost by various processes or even immobilized by micro biota. The use of isotopic enriched fertilizer is a tool that allows the evaluation of N of the fertilizer in component of the system, such as in the residue of forage, in soil and in the plant. This research was conducted to evaluate the growth and productivity of coffee plant, elaborate the N balance and evaluate the decomposition of biomass of Brachiaria under the canopy the crop as a source of this nutrient. The Brachiaria biomass under the coffee plant canopy reduced by 49% the water loss in dry months, with an increase in plant growth within the dry season that went throw March to September 2011. The gain in fruit development and the plant productivity were higher when applied an N doses of 50% within the coffee plant and 50% on the Brachiaria, which the wastes were deposited under the canopy of the crop for decomposition. The forage Bracharia recovered more N (84.28% of the applied or 126.42 kg ha-1) than coffee plant (38.63% or 57.94 kg N ha-1) with the application of the same dose of N in both plants. The N of the fertilizer recovered by the coffee plant was: 38.63% when all N was supplied to the plant, 14.31% (21.46 kg ha-1) when the application was made only in forage residue which was deposited under canopy of the plant, 53.3% (39.98 kg ha-1) from the fertilizer and other 15.28% (11.46 kg ha-1) from the decomposition of biomass in the application of the same dose of N in culture and forage. The growth rate of coffee plant (height and productive branches) in the dry season was superior when the culture and the forage received the same doses of N. The total net competition on N between the culture and Brachiaria was low, about 0.91 kg ha-1 to 0.34 kg N ha-1 (1.22 to 0.24%), not prejudicing the culture growth and productivity. The N loss due to leaching was higher when provided only to the coffee plant (6.05% of N applied or 9.07 kg ha-1) comparing to applying N exclusively to the brachiaria (1.02% or 1, 53 kg N ha-1). When applying equal doses in coffee plant and brachiaria the leaching varied from 3.4% of applied N (2.55 kg ha-1) under the canopy of the plant to 1, 15% (0.86 kg ha-1) in the forage area, grown between the crop rows. The rate of decomposition of the residue of Brachiaria was inversely proportional to the relations C / N and lignin / N. The cycling of N was faster when the reaping occurred up to 55 days of forage development.

O nitrogênio (N) é o nutriente exigido em maior quantidade pelo cafeeiro e o segundo mais exportado pelos grãos. O uso do consórcio entre o cafeeiro e a braquiária é cada vez mais usado pelos cafeicultores. Nesse sistema de produção a fertilização é feita, em geral, nas duas espécies, sem conhecimento suficiente que respalde esse manejo. O N do resíduo vegetal pode ser absorvido pela planta após a mineralização, ser perdido por vários processos, ou ainda, ser imobilizado pela microbiota. O uso de fertilizantes enriquecidos isotopicamente é uma ferramenta que permite avaliar o N do fertilizante nos componentes do sistema, como no resíduo da forrageira, no solo e na planta. Essa pesquisa foi realizada com o objetivo de avaliar o crescimento e a produtividade do cafeeiro; elaborar o balanço de N; e avaliar a decomposição da biomassa da braquiária sob a copa do café, como fonte desse nutriente. A biomassa da braquiária sob a copa do cafeeiro reduziu em 49% a perda de água nos meses secos, com aumento do crescimento da planta entre março e setembro de 2011. A granação dos frutos e a produtividade do cafeeiro foram superiores quando aplicou-se 50% da dose do N na planta e os outros 50% na braquiária, cujo resíduo foi depositado sob a copa da planta, para a decomposição. A forrageira recuperou mais N (84,28% do aplicado ou 126,42 kg ha-1) do que o cafeeiro (38,63% ou 57,94 kg ha-1 de N), com a aplicação da mesma dose de N em ambas as plantas. O cafeeiro recuperou 38,63% do N do fertilizante, quando todo o N foi fornecido à planta; recuperou 14,31% do N (21,46 kg ha-1) na aplicação feita somente na forrageira, em que o resíduo foi depositado sob a copa da planta; e recuperou 53,3% do N (39,98 kg ha-1) do adubo e outros 15,28% (11,46 kg ha-1) proveniente da decomposição da biomassa, na aplicação da mesma dose de N na cultura e na forrageira. A taxa de crescimento do cafeeiro (altura e ramos produtivos) no período seco, de março a setembro de 2011, foi superior quando a planta e a forrageira receberam a mesma dose de N. A competição líquida por N entre a braquiária e o café foi pequena e variou de 1,22% (0,91 kg ha-1) a 0,24% (0,34 kg ha-1 de N), sem prejuízo ao crescimento e à produtividade do cafeeiro. A perda de N por lixiviação foi maior quando forneceu todo o N somente no cafeeiro (6,05% do N aplicado ou 9,07 kg ha-1), em relação à adubação feita apenas na braquiária (1,02% ou 1,53 kg ha-1 de N); e, na aplicação de doses iguais no café e na braquiária, a lixiviação variou de 3,4% do N aplicado (2,55 kg ha-1) sob a copa da planta a 1,15% (0,86 kg ha-1) na área da forrageira, cultivada na entre linha da cultura. A biomassa da braquiária fertilizada com N possuia menores relações lignina/N e C/N; e a mineralização do N foi mais rápida do que a decomposição da biomassa. A ciclagem do N depende da época de corte, com maior intensidade quando a ceifa ocorreu entre 30 e 55 dias na braquiária fertilizada e até 30 dias após rebrota, quando não recebeu N. / Nitrogen (N) is the nutrient required in larger quantities by coffee and the second most exported by the grains. The use of intercropping coffee and the Brachiaria is increasing within coffee farmers. In this production the fertilization is done generally in both species, without enough knowledge support for this. The N of the plant residue can be absorbed by the plant after mineralization, can be lost by various processes or even immobilized by micro biota. The use of isotopic enriched fertilizer is a tool that allows the evaluation of N of the fertilizer in component of the system, such as in the residue of forage, in soil and in the plant. This research was conducted to evaluate the growth and productivity of coffee plant, elaborate the N balance and evaluate the decomposition of biomass of Brachiaria under the canopy the crop as a source of this nutrient. The Brachiaria biomass under the coffee plant canopy reduced by 49% the water loss in dry months, with an increase in plant growth within the dry season that went throw March to September 2011. The gain in fruit development and the plant productivity were higher when applied an N doses of 50% within the coffee plant and 50% on the Brachiaria, which the wastes were deposited under the canopy of the crop for decomposition. The forage Bracharia recovered more N (84.28% of the applied or 126.42 kg ha-1) than coffee plant (38.63% or 57.94 kg N ha-1) with the application of the same dose of N in both plants. The N of the fertilizer recovered by the coffee plant was: 38.63% when all N was supplied to the plant, 14.31% (21.46 kg ha-1) when the application was made only in forage residue which was deposited under canopy of the plant, 53.3% (39.98 kg ha-1) from the fertilizer and other 15.28% (11.46 kg ha-1) from the decomposition of biomass in the application of the same dose of N in culture and forage. The growth rate of coffee plant (height and productive branches) in the dry season was superior when the culture and the forage received the same doses of N. The total net competition on N between the culture and Brachiaria was low, about 0.91 kg ha-1 to 0.34 kg N ha-1 (1.22 to 0.24%), not prejudicing the culture growth and productivity. The N loss due to leaching was higher when provided only to the coffee plant (6.05% of N applied or 9.07 kg ha-1) comparing to applying N exclusively to the brachiaria (1.02% or 1, 53 kg N ha-1). When applying equal doses in coffee plant and brachiaria the leaching varied from 3.4% of applied N (2.55 kg ha-1) under the canopy of the plant to 1, 15% (0.86 kg ha-1) in the forage area, grown between the crop rows. The rate of decomposition of the residue of Brachiaria was inversely proportional to the relations C / N and lignin / N. The cycling of N was faster when the reaping occurred up to 55 days of forage development.

Ziel der Arbeit ist die Gesamtbilanzierung der Treibhausgasemissionen eines Anbausystems unter Bewässerung auf einem Sandboden. Die dazu aufgestellte Treibhausgasbilanz basiert auf langjährigen Datenreihen zu Erträgen und Corg-Vorräten eines Dauerfeldversuchs sowie auf zweijährigen im Feldversuch durchgeführten N2O-Messungen. Die durchgeführten Untersuchungen zum Einfluss der Bewässerung auf die Corg-Vorräte zeigen, dass der Einsatz von mineralischem Stickstoffdünger und Bewässerung auf einem leichten Standort unter den klimatischen Bedingungen Nord-Ost-Deutschlands positive Effekte hat. Die N2O-Emissionen eines Sandbodens unter den klimatischen Bedingungen Brandenburgs sind sehr niedrig. Die Applikation von mineralischem Stickstoffdünger hat nur schwache und Bewässerung hat aufgrund der der hohen Bodendurchlüftung des Sandbodens keine Effekte auf die Höhe der N2O-Emissionen. Die direkten und indirekten Emissionen aus dem Maschinen- und Betriebsmitteleinsatz erhöhen sich bei Bewässerung und steigender Stickstoffdüngung deutlich. Bei den indirekten Treibhausgasemissionen nehmen die Emissionen der Herstellung des mineralischen Stickstoffdüngers einen bedeutenden Anteil der Gesamttreibhausgasemissionen ein. Bewässerung führt durch den erhöhten Dieselverbrauch hauptsächlich zu einer Erhöhung der direkten Emissionen. Unter Bewässerung kann jedoch ein Teil der Emissionen durch zunehmende Corg-Vorräte kompensiert werden. Somit sind in einigen Fällen die Gesamttreibhausgasemissionen pro Hektar bei Bewässerung geringer als ohne Bewässerung. Die aus Stickstoffdüngung und Bewässerung resultierenden Ertragserhöhungen führen dazu, dass die Gesamttreibhausgasemissionen bezogen auf die Ertragseinheit in den meisten bewässerten Varianten deutlich geringer sind als in den unbewässerten. Daraus lässt sich ableiten, dass Bewässerung auf einem Sandboden zu einer Verminderung der Treibhausgasemissionen beitragen kann. / The aim of this work is the estimation of the net greenhouse gas emissions by a greenhouse balance for an irrigated cropping system on a sandy soil in north-east Germany under various nitrogen fertilizer intensities. The balances are based on data of yields and SOC stocks of an irrigated long term field experiment as well as on results of N2O-measurements over two years. The results of the analysis of the long term response of irrigation and nitrogen fertilization have shown that irrigation and mineral nitrogen fertilization led to significant increases in yields and harvest residues. The increased carbon inputs from above ground harvest residues had positive effects on the SOC stocks. The results of N2O measurements indicated that N2O emissions from a sandy soil are very low. Mineral nitrogen fertilization had only marginal effects. Irrigation showed no effects on the amount of N2O emissions. On the one hand the analysis of the prepared greenhouse gas balances showed that irrigation and increased nitrogen fertilization lead to a strong increase of direct and indirect emissions from machinery and maintenance resource use. The indirect emissions of nitrogen fertilizer production took up a main part of the net greenhouse gas emissions. Irrigation mainly increased greenhouse gas emissions of fuel use and fuel production as well as the emissions of the machinery production. On the other hand the increasing SOC stocks especially in the fertilized variants under irrigation led to a compensation of a huge part of the additional emissions. Thus, in many cases the net greenhouse gas emissions per unit area was lower under irrigation. Due to the increased yields under irrigation the net greenhouse gas emissions per unit yield were lower than that under non-irrigated conditions.

A field experiment was conducted to examine the responses in growth, total dry matter (TDM), seed yield and nitrogen (N) accumulation of Kabuli chickpea cv. Principe and narrow-leafed lupin cv. Fest to different irrigation levels and N fertilizer on a Templeton silt loam soil at Lincoln University, Canterbury, New Zealand in 2007/08. The irrigation and fertilizer treatments were double full irrigation, full irrigation, half irrigation and nil irrigation and a control, full irrigation plus 150 kg N ha⁻¹. There was a 51 % increase in the weighed mean absolute growth rate (WMAGR) by full irrigation over no irrigation. The maximum growth rates (MGR) followed a similar response. The growth rates were not significantly decreased by double irrigation. Further, N fertilizer did not significantly improve crop growth rates. With full irrigation MGRs were 27.6 and 34.1 g m⁻² day⁻¹ for Kabuli chickpea and narrow-leafed lupin, respectively. Seed yields of fully-irrigated crops were trebled over the nil irrigation treatment. With full irrigation, seed yield of chickpea was 326 and that of lupin was 581 g m⁻². Seed yield of the two legumes was reduced by 45 % with double irrigation compared with full irrigation. Nitrogen fertilizer did not increase seed yields in either legume. Increased seed yield with full irrigation was related to increased DM, and crop growth rates, seeds pod⁻¹ and seeds m⁻². Crop harvest index (CHI) was significantly (P < 0.05) increased by irrigation and was related to seed yield only in narrow-leafed lupin. With full irrigation, the crops intercepted more than 95 % of incoming incident radiation at leaf area indices (LAIs), 2.9 and 3 or greater in Kabuli chickpea and narrow-leafed lupin, respectively. In contrast, without irrigation the two legumes achieved a maximum fraction of radiation intercepted of less than 90 %. With full irrigation, total intercepted photosynthetically active radiation (PAR) was increased by 28 % and 33 % over no irrigation for Kabuli chickpea and narrow-leafed lupin, respectively. Fully-irrigated Kabuli chickpea intercepted a total amount of PAR of 807 MJ m⁻² and fully-irrigated narrow-leafed lupin intercepted 1,042 MJ m⁻². Accumulated DM was strongly related to accumulated intercepted PAR (R² ≥ 0.96**). The final RUE was significantly (P < 0.001) increased by irrigation. With full irrigation the final RUE of Kabuli chickpea was 1.49 g DM MJ⁻¹ PAR and that of narrow-leafed lupin was 2.17 g DM MJ⁻¹ PAR. Total N accumulation of Kabuli chickpea was not significantly affected by irrigation level. Kabuli chickpea total N was increased by 90 % by N fertilizer compared to fully-irrigated Kabuli chickpea which produced 17.7 g N m⁻². In contrast, total N accumulated in narrow-leafed lupin was not increased by N fertilizer but was decreased by 75 % with no irrigation and by 25 % with double irrigation (water logging) compared to full irrigation with a total N of 45.9 g m⁻². Total N was highly significantly related to TDM (R² = 0.78** for Kabuli chickpea and R² = 0.99** for narrow-leafed lupin). Nitrogen accumulation efficiency (NAE) of narrow-leafed lupin was not affected by irrigation or by N fertilizer. However, the NAE of Kabuli chickpea ranged from 0.013 (full irrigation) to 0.020 (no irrigation) and 0.017 g N g⁻¹ DM (full irrigation with N fertilizer). The N harvest index (NHI) was not affected by irrigation, N fertilizer or legume species. The NHI of Kabuli chickpea was 0.50 and that of narrow-leafed lupin was 0.51. The NHI was significantly (r ≥ 0.95 **) related to CHI.

Mid-rotation fertilization and vegetation control are some of the most common silvicultural treatments in loblolly pine (Pinus taeda L.) plantations in the southeastern United States. Competing vegetation is commonly thought to sequester fertilizer nitrogen (N) and reduce the potential growth response to a mid-rotation fertilization treatment. This experiment aims to identify what proportion of applied N fertilizer is retained in the crop tree pine foliage, and the degree to which understory vegetation is competing for this resource. Our mid-rotation loblolly pine plantation received an application of 15N fertilization (urea 365 kg/ha, at 46% N by weight, i.e. 168 kg/ha of N) and a portion of plots received an understory vegetation control (basal spray application of triclopyr; 13.6% active ingredient) treatment either before fertilization or not at all. One-year post-fertilization, 15N contents within pine foliage, leaf fall/leaf litter, forest floor, and soil were measured, as was competing vegetation presence. There was significant variation in applied nitrogen acquisition among the different ecosystem components measured, with 0-15 cm soils retaining a majority at 32-37% added 15N. Differences in fertilizer N acquisition in pine foliage between plots with and without understory vegetation control was marginally significant (p = 0.06) with pine foliage in plots without understory vegetation capturing greater 15N (4.3% greater). Red maple (Acer rubrum) and oak species (Quercus spp.) were the most common competitors but neither had a uniquely pronounced effect on pine nitrogen sequestration. My data indicate that increasing competition reduces fertilizer N foliar concentrations in crop pine trees but at a modest rate and equally across species groups. An unrefined threshold determining when fertilizer N capture in crop pine trees was affected was found at 3.1 m2/ha of competing vegetation basal area. This site will continue to be monitored over time to assess fertilizer N retention in loblolly pine each year after fertilization and evaluate the fertilizer N capture within competing vegetation. / Master of Science / Some of the most prevalent management practices for mid-rotation (age 15, i.e., roughly halfway through a crop cycle) loblolly pine (Pinus taeda L.) plantations in the southeastern United States are fertilization and vegetation control. Nitrogen (N) is consistently one of the most limiting factors to productivity. The addition of N via fertilization is therefore a common forestry practice. However, when a stand is fertilized, the added resource is partitioned and cycled throughout the ecosystem. It is presumed that the amount of fertilizer N obtained by crop trees in a plantation is dependent on the level of competing vegetation (i.e., weed-trees and shrubs) present on site. Controlling competing vegetation prior to fertilization may therefore be warranted under certain conditions. To date, the amount of competing vegetation where it begins to impact fertilizer uptake by the crop tree is unknown. This study aims to elucidate this competing vegetation threshold to better inform mid-rotation management of loblolly pine plantations. This study examined applied fertilizer N capture in ecosystem components with varying levels of understory vegetation, and found more fertilizer N in pine foliage when understory vegetation was completely removed prior to fertilization. No single understory hardwood weed species had a uniquely strong influence on crop tree productivity uptake. Plots that ranked in the upper third in competing vegetation presence did have significantly less foliar fertilizer N in the pine crop trees. Additional replication of this study would be necessary to determine a universal threshold of competing vegetation which would trigger the removal of competing vegetation prior to fertilization.

Mit dem wachsenden Energiebedarf der Weltbevölkerung, Problemen mit der Kernenergie und begrenzten fossilen Energieträgern ergibt sich die Notwendigkeit, alternative ökonomische und nachhaltige Energiequellen zu suchen. Weiden und Pappeln im Kurzumtrieb können als Bestandteil des Erneuerbaren Energiemix eine Ergänzung zu wind- und sonnenscheinabhängigen Anlagen sein. Im Vergleich zu 1-jährigen Ackerkulturen haben sie geringere Ansprüche an Dünger, Herbizide, Pflanzenschutzmittel und die Bodenbearbeitung. Für die Umwelt- und Energiebilanz sind die im Herstellungsprozess eingesetzte Energie und der verwendete Dünger relevant. Auf Brandenburger Ackerstandorten war für die Kurzumtriebsgehölze Weiden und Pappeln bisher nicht sicher, ob der Einsatz des N-Düngers Kalkammonsalpeter zur Steigerung der Erträge führt und welche Umweltwirkungen damit verbunden sind. Deshalb wurde in Potsdam-Bornim ein randomisierter Blockversuch mit Weiden (Salix viminalis Klon Inger) und Pappeln (Populus maximovizcii x Populus nigra Klon Max 4) im Kurzumtrieb in 2-jähriger Rotation und 4 Wiederholungen auf durchschnittlich mit Nährstoffen versorgtem Brandenburger Ackerland auf Pseudogley-Braunerde mit schwach lehmigem Sand in den Düngestufen 0 kg N ha-1a-1, 25 kg N ha-1a-1, 50 kg N ha-1a-1 und 75 kg N ha-1a-1 angelegt. Zusätzlich wurde eine mit 50 kg N ha-1a-1 gedüngte Variante untersucht, die von Begleitflora frei gehalten wurde. In den ersten 4 Vegetationsjahren wurden die Ertragseinflüsse der mineralischen N-Düngung sowie die N-Auswaschung, die Pflanzengesundheit, die Begleitflora und die N2O-Emissionen erfasst. Die Begleitflora im ersten Rotationszyklus hatte einen signifikant negativen Einfluss auf die Erträge von Pappeln und Weiden. Die Menge an Begleitflora und deren N-Gehalte stiegen mit steigenden N-Düngemengen. Der N-Dünger führte im Gesamtuntersuchungszeitraum bei Pappeln und Weiden weder zu Mehrerträgen noch zu unterschiedlichen N-Gehalten in Blättern oder Stämmen, weil er zu großen Anteilen ausgewaschen oder von der Begleitflora aufgenommen wurde. Die düngeinduzierten N2O-Emissionen in Weiden- und Pappelparzellen lagen unter 0,3 kg N ha-1a-1. Der von den Weiden und Pappeln benötigte N wurde in den ersten 4 Jahren durch Deposition, Mineralisation, verlagertes N aus tieferen Bodenschichten, Mykorrhizierung, bakterielle N2-Fixierung sowie endophytische Bakterien bereitgestellt. Der Verzicht auf N-Dünger vermindert die Konkurrenz der Begleitflora um Wasser und Nährstoffe, die N-Auswaschungsverluste, düngeinduzierte Treibhausgasemissionen sowie die energieaufwendige Herstellung von synthetischem N. Die Pflanzengesundheit wurde durch die Düngung nur geringfügig beeinflusst. Am Versuchsstandort wurden Pappeln mehr durch Rost (Melampsora ssp.) und Blattfraß geschädigt als Weiden. Die Fraßschäden wurden hauptsächlich von Roten Pappelblattkäfern (Chrysomela populi) und Blauen Weidenblattkäfern (Phratora vulgatissima / Phratora ssp.) verursacht. Weiden wurden stärker von Zikaden befallen als Pappeln.

Beim Parameter „Druscheignung“ eines Bestandes wird gemeinhin angenommen, dass dieses Kriterium durch die Genetik der Sorte und den Witterungsverlauf, weitgehend unbeeinflusst von Landwirt, festgelegt ist. Und dennoch verändert der Landwirt mit all seinen Entscheidungen von der Auswahl der Sorten, über die Düngung, den Pflanzenschutz bis hin zum Erntemanagement die Druscheignung stetig. Zur Ernte, als letzten Abschnitt der Verfahrenskette, entfaltet die Druscheignung dann außerordentlich große ökonomische Auswirkungen. Anhand verschiedener Beispiele aus Züchtung, Pflanzenernährung, Pflanzenschutz und Erntetechnologie wurde dargestellt, wie auf die Druscheignung Einfluss genommen werden kann und wie diese Auswirkungen monetär zu bewerten sind. Aus dem Bereich der Züchtung wurde die Entwicklung eines neuen Wuchstyps bei den Rapshalbzwergen ausgewählt, der mit weniger Biomasse konkurrenzfähige Erträge erzielt. Die Abreife ist einheitlicher, der Erntetermin kann problemloser fixiert werden, der Drusch ist leistungsstark und verlustarm. Späte und intensiv geführte Sorten sind mit Hilfe einer Sikkation zeitlich früher und leichter zu beernten. Das schafft Erntesicherheit bei geringeren Verlusten, höheren Mähdrescherleistungen und sinkendem Kraftstoffverbrauch. Die bedarfsgerechte Ausbringung des Stickstoffs in Art, Menge und Zeit, entsprechend der kleinräumigen Heterogenität eines Schlages, führt zu einer Homogenisierung der Bestände. Die Bestände reifen gleichmäßiger ab und führen zu etwa 20 Prozent höherer Mähdrescherleistung sowie geringerem Kraftstoffverbrauch. Am Beispiel des Hochschnitts wurde verdeutlicht, wie sich die bessere Beerntbarkeit auf Maschinenkosten, Gesamternteverluste, Qualität und Trocknung auswirkt. Hebt man die Stoppellänge um 10 Zentimeter an, lässt sich die Mähdrescherleistung um ca. 15 bis 20 Prozent steigern. Diese Beispiele unterstreichen zugleich die Forderung, dass die Druscheignung nicht erst zur Ernte diese Führungsrolle übernimmt, sondern auch in den vorgelagerten Verfahrensabschnitten als ein starkes Entscheidungskriterium gelten muss. / The parameter “threshability” of a stand is commonly assumed to be a criterion defined by the genetics of the strain and the weather conditions which is mainly not influenced by the farmer. Nevertheless, the farmer continuously changes the “threshability” with all his decisions, from the selection of the strains, via the use of fertilizers to the harvest management. For harvest, as the last stage of the process chain, the threshability develops extraordinarily high economic effects. On the basis of several examples from cultivation, plant nutrition, plant protection and harvest technology it was described, how the threshability can be influenced and how this effect is to be assessed monetarily. In the field of cultivation, the development of a new growth type of semi-dwarf rape has been selected, which yields competitive returns with less bio mass. Ripeness is more homogeneous, the harvest date can be fixed without problems, threshing is efficient and with low loss. Using the method of siccation, late and intensively controlled strains can be harvested earlier and easier. This offers harvest safety with low loss, higher combine harvester performance and reduced fuel consumption.The need-based spreading of nitrogen referring to type, quantity and time according to the small-scale spatial heterogeneity of a field leads to a homogenisation of the stands. The stands ripen more evenly and this fact causes about 20 percent higher combine harvester performance, as well as reduced fuel consumption. Using the example of high-cut top harvest it was clarified how the better harvestability influences the machine costs, the total harvest losses, the quality, and the drying process. If the length of the stubbles is extended by 10 centimetres, the combine harvester performance can be increased by 15 to 20 percent. These examples also emphasize the requirement that the threshability does not just take over the leading role for the harvest but has also to be considered as a strong decision criterion within the prior stages of the process.

Cereal rye (CR), the most common and effective nitrogen (N) scavenging cover crop option in the Midwest, is often utilized in cropping systems to reduce nitrate loss for environmental benefits. To increase environmental efficiency in Midwest corn cropping systems, we must increase the overall adoption of CR. However, due to the yield reduction potential (6%) for corn planted after CR termination, CR is primarily recommended before soybean. To increase CR adoption, we must develop adaptive fertilizer management practices that achieve competitive grain yields relative to cropping systems where CR is not adopted. Therefore, the objectives of this study are to determine (1) the effect of CR and starter nitrogen rate on corn growth and nitrogen content. (2) the optimum starter nitrogen rate to achieve agronomic optimum corn yield following CR. (3) the impact of phosphorus (P) at starter on plant growth, nitrogen content, and yield with the inclusion of CR. For our study, five starter N rates were applied in a 5x5 cm band to both CR and non-CR plots, concentrations ranged from 0-84 kg N ha^-1in 28 kg N ha^-1 intervals. Total N applied was the same for each treatment, relative to its location, and was split between starter N at planting and sidedress applied at growth stage V6 relatively. Although CR termination took place at least two weeks before planting, CR decreased corn grain yield at one of three locations by an average of 8%, nitrogen recovery efficiency (NRE) by 27%, and R6 total N content by 23%, relative to the conventional control (non-CR 0N), when no starter N was applied. At one of three locations, starter N rates of 56 kg N ha^-1, 56 kg N ha^-1plus 17 kg P ha^-1, and 84 kg N ha^-1 increased corn grain yield, in CR plots, and 56 kg N ha^-1 plus 17 kg P ha^-1 increased corn grain yield in non-CR plots. Phosphorus increased corn grain N content at growth stage R6 in one of three locations and did not impact corn grain yield at all locations. We conclude that the inclusion of starter N at planting has the potential to increase agronomic productivity in CR corn cropping systems in soil environments with a high capacity to mineralize soil N. However, further research is required to refine our starter N results to find an optimum starter N rate to apply before planting corn following CR.