Greater Economic Returns Research Articles

Economic, Production, and Poverty Impacts of Investing in Maize Tolerant to Drought in Africa: An Ex-Ante Assessment

The potential impacts of investing in drought tolerant maize (DTM) in 13 countries of eastern, southern and western Africa were analyzed through an innovative economic surplus analysis framework, to identify where greatest economic returns and poverty reduction may be achieved. Assuming a potential full replacement of improved varieties with DTM varieties, by 2016 there would be economic gains of US$ 907 million over all countries under conservative yield gains, or US$ 1,535 million under optimistic yield gains. Largest gains in terms of consumer and producers surplus are in Nigeria, Zimbabwe and Malawi. However, in terms of production gains and poverty reduction, the countries gaining most are Nigeria, Kenya and Malawi (in terms of production); and Zimbabwe, Malawi and Kenya (number of people out of poverty). A total of 4 million people — both producers and consumers— would have their poverty greatly reduced in all countries. To achieve these impacts, deployment strategies are discussed and various options are suggested, which depend on local context and state of the national seed sectors.

Rumen fermentation and performance of lactating dairy cows affected by physical forms and urea treatment of rice straw.

The aim of this study was to determine the effect of different physical forms and urea treatment of rice straw on feed intake, rumen fermentation, and milk production. Four, multiparous Holstein crossbred dairy cows in mid-lactation with initial body weight (BW) of 409±20 kg were randomly assigned according to a 4×4 Latin square design to receive four dietary treatments. The dietary treatments were as follows: untreated, long form rice straw (LRS), urea-treated (5%), long form rice straw (5% ULRS), urea-treated (2.5%), long form rice straw (2.5% ULRS) and urea-treated (2.5%), chopped (4 cm) rice straw (2.5% UCRS). Cows were fed with concentrate diets at a ratio of concentrate to milk yield of 1:2 and rice straw was fed ad libitum. The findings revealed significant improvements in total DM intake and digestibility by using long and short forms of urea-treated rice straw (p<0.05). Ruminal pH was not altered among all treatments (p>0.05), whereas ruminal NH3-N, BUN and MUN were found to be increased (p<0.01) by urea-treated rice straw as compared with untreated rice straw. Volatile fatty acids (VFAs) concentrations especially those of acetic acid were decreased (p<0.05) and those of propionic acid were increased (p<0.05), thus acetic acid:propionic acid was subsequently lowered (p<0.05) in cows fed with long or short forms of urea-treated rice straw. The 2.5% ULRS and 2.5% UCRS had greater microbial protein synthesis and was greatest when cows were fed with 5% ULRS. The urea-treated rice straw fed groups had increased milk yield (p<0.05), while lower feed cost and greater economic return was in the 2.5% ULRS and 2.5% UCRS (p<0.01). From these results, it could be concluded that 2.5% ULRS could replace 5% ULRS used as a roughage source to maintain feed intake, rumen fermentation, efficiency of microbial protein synthesis, milk production and economical return in mid-lactating dairy cows.

ABALONE POACHING: A PHILOSOPHICAL APPROACH

The question that I raise is whether one’s judgment, in other words, knowing the difference between right and wrong, can be clouded by monetary rewards, especially with regard to criminal activity. I take a philosophical approach with specific focus on the environmental concern of abalone poaching. I draw parallels and theoretical answers from Karl E Klare’s ‘Legal culture and transformative constitutionalism’, James Boyd White’s ‘Justice in tension: an expression of law and the legal mind’, John Dugard’s ‘The judicial process, positivism and civil liberty’ and the theories of judgment of Hannah Arendt. Environmental crime is a rising epidemic, especially in South Africa. I argue that not enough attention is paid to such crimes. Sensational crimes seem to have an increased popularity in the press and environmental crimes seem to go deprioritised. There appears to be very few viable solutions for crimes that yield great economic returns. In the mind of the offender, the motivation of great economic returns can be said to override the sense of morality or judgment.

Fornecimento de grão de milheto, inteiro ou triturado, em duas frequências de suplementação para bovinos de corte

Objetivou-se avaliar o processamento do grão de milheto inteiro ou triturado em suplementos fornecidos diariamente ou três vezes por semana para bovinos de corte em pastejo e seus efeitos sobre o desempenho produtivo e econômico e o comportamento ingestivo diurno durante o período da seca. Utilizaram-se 25 bovinos nelores não-castrados, com peso inicial de 350,92±31,7 kg, mantidos em cinco piquetes com área unitária de 1,45 ha formados por B. brizantha cv Marandu. Os animais foram distribuídos em delineamento inteiramente casualizado em esquema fatorial 2 × 2 + 1, composto de duas formas físicas do grão de milheto (inteiro ou triturado), duas frequências de suplementação (diária ou três vezes por semana) e um tratamento controle (mistura mineral). A suplementação concentrada promoveu ganho de peso, enquanto a suplementação apenas com minerais acarretou perdas de peso de 0,16 kg/animal/dia. A moagem do grão de milheto proporcionou maiores ganhos (0,36 e 0,38 kg/animal/dia nos grupos com suplementação 3 e 7 vezes por semana, respectivamente), em comparação ao fornecimento de grão inteiro (0,22 e 0,24 kg/animal/dia, 3 e 7 vezes por semana, respectivamente), enquanto as frequências de suplementação estudadas não promoveram diferenças nestas variáveis. Foi encontrado efeito significativo da interação dia × tratamento para tempo gasto com consumo de suplemento, pastejo e hidratação. Para o tempo em ócio, foi encontrada diferença entre o grupo controle e os demais. Maior retorno econômico foi obtido quando se ofertou milheto triturado e em menor frequência de suplementação (R$ 22,70/animal). A utilização de suplementos múltiplos, assim como o processamento do grão de milheto, possibilita maiores ganhos de peso, independentemente da frequência de suplementação estudada, sendo que o fornecimento de suplemento 3 vezes por semana reduz os custos da suplementação.

Long-term Effects of Peach Production Systems for Standard and Pillar Growth Types on Yield and Economic Parameters

The lack of dwarfing rootstocks for peach has led to cultural and genetic approaches that reduce tree size and vegetative growth to establish high-density plantings. The objectives of the study were to evaluate the interactions of pruning strategies, groundcover management, tree densities, and peach (Prunus persica) architecture combined in eight peach production systems on components of yield and economic value. The use of sod management reduced pruning time and costs, but the reduction of crop load reduced net return. High-density plantings in large vegetation-free areas (VFAs) had greater economic return than low-density plantings.

Research on the New Compound Technology of Integral Seamless Housing of Rear Axle

In order to save energy and material, and reduce productive costs, in accordance with the geometrical characteristics of rear axle housing of trucks, the redesign of integral product with new technology was completed, and then, two kinds of forming technology were developed. Afterwards, rear axle housing of light trucks was formed by adopting hydraulic bulging and neck-spinning, and the housing of heavy trucks by adopting hot mechanical expanding and hot neck-spinning with the tube. The research of this paper has practical value and results in great economic returns.

EVALUATION OF DIFFERENT ROCKWOOL FIBERS FOR TOMATO GROWN UNDER GREENHOUSE CONDITIONS IN ALMERÍA: EFFECTS ON PRODUCTION AND QUALITY

The tomato (Solanum lycopersicum L.) is a globally important vegetable, with Spain being one of the most important countries in tomato production. Almeria is one of the main producing areas of fresh tomato and is the leading exporter of tomato. Therefore this vegetable provides the greatest economic returns in intensive horticulture. Soilless culture has increased the potential to grow in soils with inadequate physical and chemical properties and/or the persistence of soil diseases, with rockwool being the substrate that is used by nearly 50% of crops grown without soil. The trial was conducted in a semi-cylindrical greenhouse structure in the Experimental Farm Fundacion Universidad de Almeria-ANECOOP, Almeria (Spain). The cultivar 'Pitenza' (cluster-type) was cultivated in short crop cycle cultivation on two substrates with different rockwool fiber thickness (FN70 and FG70) and two different planting distances (2.0 × 0.25 and 1.66 × 0.25). Subsequently the cultivar 'Salomee' was grown in long crop cycle on four types of rockwool (FN65, FG65, FN70 and FG70) and two different cultivation planting distances (2.0 × 0.65 and 1.66 × 0.5). In both trials, parameters of production and quality of fruit were measured. The trials between different rockwool thicknesses revealed that the fine fibers provide some early production benefit, but thicker fibers increase the final yield of the crop. Planting density does not influence production significantly when the crop cycle is short, but production per unit area increases in long crop cycles when planting distance increases. Productivity per unit area is of greatest interest to the farmer. The quality parameters were not influenced by the different treatments.

Water Security: Why It Matters and What to Do about It

their food, produce their energy, and sustain their bodies. Rich and poor countries face different hydrological challenges (see figure 1, next page): rainfall in most rich countries is moderate and predictable, whereas many poor countries suffer more frequently from droughts and floods and face higher levels of uncertainty. Compounding the “bad hydrology” problem, most poor countries face a rapid growth in water demand, have small endowments of water infrastructure, have fragile institutions, and confront ever greater variability as the world climate changes. The result is growing water insecurity and more conflicts within and between countries, with the gravest challenges in and between poor countries. The glass is certainly half empty. But it is also half full, as there is emerging evidence (a) that societies with adequate stocks of infrastructure and robust institutions can adjust to major climatic shocks relatively harmoniously and with modest economic consequences, and (b) that there is huge potential in the development of a new generation of “smart technologies” (involving infrastructure, biology, chemistry, information, finance) for getting greater economic return from constrained supplies. In short, faced with unprecedented water-security challenges, there is an urgent need for all countries, and especially poor ones, to develop suites of institutions and technologies that are adapted to their cultural, historic, natural, and financial realities and which can bring their people improved and more harmonious development.

Effects and economic implications of metaphylactic treatment of feeder cattle with two different dosages of tilmicosin on the incidence of bovine respiratory disease (BRD)

Two studies were conducted to evaluate the efficacy of tilmicosin for metaphylactic treatment of bovine respiratory disease (BRD), and subsequent effects on calf performance, in newly received, high-risk feedlot cattle. Calves in each study were randomly assigned to one of three treatment groups: negative control; 4.55 mg/lb body weight (BW) (10 mg/kg BW) tilmicosin (TIL10); or 9.1 mg/lb BW (20 mg/kg BW) tilmicosin (TIL20). In Study I, calves receiving tilmicosin had lower BRD morbidity (P&lt;0.01) and mortality rates (P=0.02) compared to controls. Furthermore, BRD morbidity was lower (P≤0.05) in the TIL20 (16.8%) compared to the TIL10 (24.3%) group. Average daily gain was improved (P&lt;0.01) in both tilmicosin metaphylaxis treatment groups compared to controls when deads and removals were not included in the final calculations (2.9 lb and 3.0 lb vs 2.8 lb or 1.32 kg and 1.36 kg vs 1.27 kg), as well as when deads and removals were included in the evaluation (2.7 lb and 2.8 lb vs 2.4 lb or 1.23 kg and 1.27 kg vs 1.09 kg, respectively). Calves treated metaphylactically with tilmicosin had greater economic return per pen (P&lt;0.01) than did controls. In Study II, calves in both TIL10 and TIL20 treatment groups had lower (P≤0.05) morbidity compared to controls (68.5, 49.9, and 44.0% for control, TIL10, and TIL20, respectively). No significant differences in performance were observed between treatment groups.

Cotton Harvest at 40% Versus 75% Boll-Splitting on Yield and Economic Return under Standard and Proactive Boll Weevil (Coleoptera: Curculionidae) Spray Regimes

The standard practice of two or three preemptive insecticide applications at the start of pinhead (1-2-mm-diameter) squaring followed by threshold-triggered (when 10% of randomly selected squares have oviposition punctures) insecticide applications for boll weevil, Anthonomus grandis grandis Boheman (Coleoptera: Curculionidae), control does not provide reliable protection of cotton, Gossypium hirsutum L., lint production. This study, conducted during 2004 and 2005, showed that three to six fewer spray applications in a "proactive" approach, in which spraying began at the start of large (5.5-8-mm-diameter) square formation and continued at approximately 7-d intervals while large squares were abundant, resulted in fewer infested squares and 1.4- to 1.7-fold more lint than the standard treatment. Fewer sprays and increased yield made proactive spraying significantly more profitable than the standard approach, which resulted in relatively low or negative economic returns. Harvest at 75% boll-split in the proactive spray regime of 2005 resulted in four-fold greater economic return than cotton harvested at 40% boll-split because of improved protection of large squares and the elimination of late-season sprays inherent to standard spray regime despite the cost of an extra irrigation in the 75% boll-split treatments. The earlier, 40% harvest trigger does not avoid high late-season boll weevil pressure, which exerts less impact on bolls, the predominant form of fruiting body at that time, than on squares. Proactive spraying and harvest timing are based on an important relationship between nutrition, boll weevil reproduction, and economic inputs; therefore, the tactic of combining proaction with harvest at 75% boll-split is applicable where boll weevils are problematic regardless of climate or region, or whether an eradication program is ongoing.

Responses to grain:sunflower meal supplements by weaned calves grazing mature pasture or eating hay in pens

In southern Australia, winter-born calves may not be at marketable weights until 18 months of age and can thus compete with their dams and the next crop of calves for the pasture resource. We investigated supplementary feeding options to improve calf liveweight gains and overcome this problem. Weaned beef calves confined to feedlots for 70 days were fed different ratios (1 : 1 up to 1 : 4) of sunflower meal to oat grain (Experiment 1) or barley grain (Experiment 2) at levels of 3–6 kg air-dry/day, plus either oaten hay (Expt. 1) or pasture hay (Expt. 2) fed ad libitum. Liveweight gains at 3 kg supplement/day were ~1.2 kg/day at all ratios and were slightly higher at the higher feeding levels. The intake of hay varied inversely with the amount of supplement fed and substitution rates were 0.49 with oaten hay and 0.47 with pasture hay. Total DM intakes did not decline in Experiment 1 as supplement intake increased and increased in Experiment 2 with increasing supplement intake. A separate group of calves that had been grazing mature pasture while their cohorts were in the feedlot showed good compensatory growth when transferred to good pasture, whereas calves coming out of the feedlot onto the same pasture initially lost weight before regaining weight. This suggests that such feedlot-reared calves should be sold direct from the feedlot. In a third experiment, over 2 years, weaned calves grazed mature summer pasture for 81 days and were fed 0, 1, 2, 3 or 5 kg/day of a 1 : 2 ratio of sunflower meal : hammer-milled oat grain. Weight gains were less than in Experiments 1 and 2 and responses of gain to supplement intake were curvilinear. Gains did not exceed 0.75 kg/day and peaked at supplement intakes of 4.3 and 2.8 kg DM/day in years 1 and 2, respectively. Liveweight gains/kg supplement consumed were similar to those in previous studies. A preliminary assessment of supplement costs and the economic value of liveweight gain showed a curvilinear response to supplement intake and suggested that the greatest economic return resulted from an intake of 1.9–2.4 kg/day of the supplement, lower than the supplement intakes for maximum liveweight gain.

Texas Panicum (Panicum texanum) Control in Irrigated Field Corn (Zea mays) with Foramsulfuron, Glyphosate, Nicosulfuron, and Pendimethalin

Texas panicum is considered to be the most troublesome weed of field corn in the Southeast. Field trials were conducted in Georgia in 2003 and 2004 to compare pendimethalin, nicosulfuron, foramsulfuron, and glyphosate for Texas panicum control in irrigated field corn and to determine which herbicide provided the greatest economic returns. Pendimethalin applied early POST (EPOST), 10 to 12 d after planting (DAP), controlled Texas panicum less than 35% late in the season and resulted in reduced corn yield and net returns in 2004. Glyphosate applied sequentially POST at 21 to 24 DAP and again late POST (LPOST) at 35 to 38 DAP controlled Texas panicum 82 to 94% late in the season compared with 43 to 80% control by nicosulfuron and foramsulfuron applied POST. Texas panicum control, corn yield, and net returns were similar with glyphosate applied POST and LPOST at 0.53 or 1.1 kg ai/ha. Glyphosate applied POST and LPOST was more effective than glyphosate POST, but net returns were greater only in 2004.

An economic comparison of alternative and traditional cropping systems in the northern Great Plains, USA

AbstractCurrent production practices in the Red River Valley of North Dakota and Minnesota involve use of extensive tillage and/or herbicides to control weeds. Given the erosion potential, environmental concerns associated with herbicides, and herbicide-resistant weeds, alternative cropping systems that mitigate these problems need to be assessed economically. Furthermore, the role that government commodity programs play in the adoption of more ecologically friendly cropping systems needs to be determined. We evaluated 8 years of yield data (1994–2001) from field plots near Fargo, North Dakota, to compare the economics of two alternative cropping systems, reduced-input (RI) and no-till (NT), to a conventional tillage (CT) cropping system. The RI system relies on a more diverse rotation of soybean (SB), spring wheat (SW), sweet clover (SC) and rye, and uses fewer herbicide and fertilizer inputs than CT or NT. Both NT and CT systems rotate SB and SW. We found that CT returns averaged over $47 ha−1more than NT during the study period. Because SC yield data were not available, the economic competitiveness of RI was calculated using break-even yields and returns for SC. Historical SC yields in Cass County, North Dakota were not statistically different from the break-even yields. However, when government program payments were considered, break-even returns for SC increased by about $15 and $18 ha−1and break-even yields by 0.44 and 0.52 MT ha−1for RI to compare with NT and CT, respectively. These results indicate that CT management offers greater economic return than either RI or NT and that government program payments impede adoption of more environmentally friendly cropping systems in the northern Great Plains.

Supplementary pollination in the production of custard apple (Annona sp.) – the effect of pollen source

SummaryLow natural pollination rates produce few and poorly formed fruits in commercial orchards of the custard apple (Annona squamosa A. cherimola) cultivar ‘Hillary White’ on the Atherton Tablelands, North Queensland, Australia. To overcome this limitation, conventional practice is to hand-pollinate with pollen from either cv. ‘Hillary White’ or cv. ‘African Pride’. Supplementary pollination, using either pollen type, significantly increased overall fruit production and fruit quality above natural levels. However, pollen sourced from cv. ‘African Pride’ trees produced significantly larger and more symmetrical fruits than pollen from cv. ‘Hillary White’. Increased quality was not at the expense of quantity. There was no difference in mean fruit yield between flowers treated with pollen from either variety. These results indicate that using cv. ‘African Pride’ pollen should result in greater economic returns for growers through the production of a higher proportion of ‘best’ quality fruits.

Factors affecting carcass value and profitability in early-weaned Simmental steers: II. Days on feed endpoints and sorting strategies

In a 4-yr study, early-weaned Simmental steers (n = 192) of known genetics were individually fed to determine EPD, performance, and carcass measurements explaining variation in carcass value and profitability across incremental days on feed (DOF) when sorted by HCW, calculated yield grade (YG), or at their highest profit endpoint (BEST). Steers were weaned at 88.0 +/- 1.1 d of age, pen-fed a high-concentrate diet for 84.5 +/- 0.4 d, individually fed for 249.7 +/- 0.7 d, and slaughtered at 423.3 +/- 1.4 d of age. Carcass weight, YG, and marbling score (MS) were predicted using real-time ultrasound throughout the finishing period to calculate carcass value and profitability at 90, 60, 30 d preslaughter and under three individual sorting strategies. Sorting strategies included marketing the 25 and 50% heaviest HCW, the highest YG at d 60 and 30, or the remaining 25% at 0-d endpoints. Independent variables were year, weaning weight EPD, yearling weight EPD, marbling EPD, DMI, ADG, HCW, YG, and MS. Profit was quadratic in response to increased DOF; the greatest economic return was noted on d 30 (pre-slaughter). Final weight, DMI, HCW, MS, and YG increased (linear; P < 0.001) with additional DOF, and ADG and G:F decreased (linear; P < 0.001). Total cost of gain was quadratic (P < 0.001), and incremental cost of gain rose at an increasing rate (quadratic; P < 0.001) with increased DOF. With increasing DOF, HCW importance decreased from 58 to 21%; MS was variable, ranging from 18 to 23%; and YG and DMI were minor contributors to profit variation. Among sorting strategies, final BW and HCW were greater for BEST, whereas other measurements were similar. Sorting individuals by HCW, YG, or at BEST increased profitability 3.70 dollars, 2.52 dollars, or 30.65 dollars over the optimal group DOF endpoint (d 30). Retrospective analyses illustrated that sorting does not need to pinpoint each animal's profit optimum to result in economic gains; rather, increasing HCW and decreasing weight- and YG-related penalties improved profitability. Opportunities may exist with existing and new technology to uniformly allocate cattle into feeding and marketing groups, decrease overfeeding, and increase carcass value and profitability.

Economics of Western Juniper Control in Central Oregon

The economic and ecological benefits and control costs of western juniper (Juniperus occidentalis Hook) management on rangelands are evaluated using a discrete-time, dynamic economic model developed to depict 4 representative ranches in the John Day region of north-central Oregon. The model’s optimization criterion is to maximize the net present value of profits through decisions regarding herd size and composition, cattle sales, and the manipulation of forage production through juniper management practices. Projections are made regarding the impacts of economically optimal juniper management on wildlife populations, stream flows, and erosion levels. Results consistently showed that juniper management options resulted in larger equilibrium herd sizes and greater economic returns. Erosion levels were substantially lower in scenarios that contained juniper management options. Economically optimal juniper management decisions led to increased quail and elk populations, but generally resulted in decreased deer populations. The results indicate there are both economic and ecological benefits from controlling western juniper on Oregon rangelands. Los beneficios económicos y ecológicos del manejo del “Western juniper” (Juniperus occidentalis Hook) sobre los pastizales son evaluados usando un modelo discreto-tiempo y económico dinámico, desarrollado para describir 4 ranchos representativos de la región John Day del norte-centro de Oregon. El criterio de optimización del modelo es maximizar el valor neto presente de las ganancias a través de decisiones respecto al tamaño y composición del hato, venta de ganado y la manipulación de la producción de forraje mediante practicas de manejo del “Juniper”. Las proyecciones son hechas en relación a los impactos del manejo económicamente optimo del “Juniper” sobre las poblaciones de fauna silvestre, corrientes de agua y niveles de erosión. Los resultados mostraron consistentemente que las opciones de manejo del “Juniper” resultaron en tamaños de hato de mayor equilibrio y mayores retornos económicos. Los niveles de erosión fueron substancialmente menores en escenarios que contenían opciones de manejo del “juniper”. Las decisiones del manejo económicamente optimo del “Juniper” condujeron a mayores poblaciones de codornices y alces, pero generalmente resultaron en una disminución de las poblaciones de venado. Los resultados indican que al controlar el “Western juniper” en los pastizales de Oregon se obtienen tanto beneficios económicos como ecológicos.

Economics of Western Juniper Control in Central Oregon

The economic and ecological benefits and control costs of western juniper (Juniperus occidentalis Hook) management on rangelands are evaluated using a discrete-time, dynamic economic model developed to depict 4 representative ranches in the John Day region of north-central Oregon. The model’s optimization criterion is to maximize the net present value of profits through decisions regarding herd size and composition, cattle sales, and the manipulation of forage production through juniper management practices. Projections are made regarding the impacts of economically optimal juniper management on wildlife populations, stream flows, and erosion levels. Results consistently showed that juniper management options resulted in larger equilibrium herd sizes and greater economic returns. Erosion levels were substantially lower in scenarios that contained juniper management options. Economically optimal juniper management decisions led to increased quail and elk populations, but generally resulted in decreased deer populations. The results indicate there are both economic and ecological benefits from controlling western juniper on Oregon rangelands.

Stepwise time response of corn yield and economic return to no tillage

The adoption of no tillage (NT) in crop production has been encouraged primarily due to its more significant benefits to the environment compared with other conservation tillage systems. There are nevertheless concerns about NT corn ( Zea mays L.) performance from both short- and long-term perspectives. This study was conducted near Burlington, Nashua, Newell, Sutherland, and Crawfordsville in Iowa from 1978 through 2001 to evaluate corn production in 4- to 5-year phases under long-term NT management. Field experiments were conducted using a complete randomized block, or split-plot design. Seven tillage systems including NT, moldboard plow (MP), ridge tillage (RT), chisel plow (CP), reduced tillage (RDT), field cultivation (FC), and tillage-plant (TP) were evaluated in terms of corn yield and economic return. Differences between NT and other tillage systems in either corn yield or economic return did not change with the 4- to 5-year phases within the entire study period. The competitiveness of NT over MP, RT, CP, or other tillage systems in the early years (first 4–5 years) since tillage adoption, was as strong as that after 8–10 years. This finding is encouraging to those corn producers who are reluctant to use NT, because of their concern about the poor performance of NT corn during the early years. Yield differences between NT and other tillage systems in each 4- to 5-year phase, or averaged over the entire study period, were mostly within 5% in a corn–soybean ( Glycine max (L.) Merr.) rotation. No tillage generally had equal or greater economic return than other tillage systems in each 4- to 5-year phase and over the entire study period. The yield and economic return benefits of a corn–soybean rotation relative to continuous corn remained generally the same over time under long-term NT management. Therefore, the adoption of a NT system can be accomplished without lowering the economic return from both short- and long-term perspectives.

Assessment of Weed Control Strategies for Corn in the North-Central United States

Field experiments were conducted across the north-central United States to determine the benefits of various weed control strategies in corn. Weed control, corn yield, and economic return increased when a preemergence (PRE) broad-spectrum herbicide was followed by (fb) postemergence (POST) herbicides. Weed control decisions based on field scouting after a PRE broad-spectrum herbicide application increased weed control and economic return. Application of a PRE grass herbicide fb a POST herbicide based on field scouting resulted in less control of velvetleaf and morningglory species, corn yield, and economic return compared with a PRE broad-spectrum herbicide application fb scouting. Cultivation after a PRE broad-spectrum herbicide application increased weed control and corn yield compared with the herbicide applied alone, but economic return was not increased. An early-postemergence herbicide application fb cultivation resulted in the highest level of broadleaf weed control, the highest corn yield, and the greatest economic return compared with all other strategies. Weed control based on scouting proved to be useful in reducing the effect of weed escapes on corn yield and increased economic return compared with PRE herbicide application alone. However, economic return was not greater than the PRE fb planned POST or total POST strategies.

Stepwise time response of corn yield and economic return to no tillage

The adoption of no tillage (NT) in crop production has been encouraged primarily due to its more significant benefits to the environment compared with other conservation tillage systems. There are nevertheless concerns about NT corn ( Zea mays L.) performance from both short- and long-term perspectives. This study was conducted near Burlington, Nashua, Newell, Sutherland, and Crawfordsville in Iowa from 1978 through 2001 to evaluate corn production in 4- to 5-year phases under long-term NT management. Field experiments were conducted using a complete randomized block, or split-plot design. Seven tillage systems including NT, moldboard plow (MP), ridge tillage (RT), chisel plow (CP), reduced tillage (RDT), field cultivation (FC), and tillage-plant (TP) were evaluated in terms of corn yield and economic return. Differences between NT and other tillage systems in either corn yield or economic return did not change with the 4- to 5-year phases within the entire study period. The competitiveness of NT over MP, RT, CP, or other tillage systems in the early years (first 4–5 years) since tillage adoption, was as strong as that after 8–10 years. This finding is encouraging to those corn producers who are reluctant to use NT, because of their concern about the poor performance of NT corn during the early years. Yield differences between NT and other tillage systems in each 4- to 5-year phase, or averaged over the entire study period, were mostly within 5% in a corn–soybean ( Glycine max (L.) Merr.) rotation. No tillage generally had equal or greater economic return than other tillage systems in each 4- to 5-year phase and over the entire study period. The yield and economic return benefits of a corn–soybean rotation relative to continuous corn remained generally the same over time under long-term NT management. Therefore, the adoption of a NT system can be accomplished without lowering the economic return from both short- and long-term perspectives.