In-crop Application Research Articles

Injected Anhydrous Ammonia Is More Effective Than Broadcast Urea as a Source of Nitrogen for Drill Seeded Rice

Anhydrous ammonia is a cheaper source of nitrogen (N) fertiliser than granular urea for rice production, but it is not widely used in developing countries. It can only be applied pre-crop with any in-crop applications being applied in the form of urea. This 2-year study conducted in the Nile delta region of Egypt compared pre-crop anhydrous ammonia injected to a depth of 20 cm with broadcast urea as N sources for rice, along with 4 combinations of pre-crop ammonia and in-crop urea. Each treatment supplied a total of 165 kg N/ha. The rice crop was direct seeded rather than transplanted. The highest yields were achieved in the full anhydrous ammonia treatment, which yielded 53% more grain than the nil-N control, while the full urea treatment yielded 22% more than the control; most combination treatments were intermediate. The higher grain yield of the anhydrous ammonia treatment was through a higher panicle density per unit area and more filled grains per panicle. An economic analysis found that the anhydrous ammonia treatment had a net return 70–94% higher than supplying the same quantity of N as urea. Counts of bacteria, fungi and actinomycetes showed a decline by day 2 after injection of anhydrous ammonia, followed by an increase to numbers similar to or above pre-injection levels by day 5. The findings indicated that pre-crop anhydrous ammonia in rice is both economically promising and not deleterious to soil microbes.

Utility of isoxaflutole-based herbicide programs in HPPD-tolerant cotton production systems

AbstractPalmer amaranth has developed resistance to at least seven herbicide sites of action in the Cotton Belt of the United States, leaving producers with fewer options to manage this weed. Previous research with corn and newly commercially released soybean systems have found the use of 4-hydroxyphenylpyruvate dioxygenase (HPPD)-inhibiting herbicides such as isoxaflutole (IFT) to be effective at managing Palmer amaranth. Consequently, a new transgenic cultivar of cotton is being developed with tolerance to IFT, allowing for in-crop applications of the herbicide. Two separate studies were conducted near Marianna, AR, in 2019 and replicated in 2020, to investigate the crop safety and utility of IFT when added to cotton herbicide programs. Herbicide programs featured IFT as a preemergence or early-postemergence option, residual herbicides in subsequent postemergence applications, and the presence or absence of a layby application. The use of IFT did not significantly impact cotton injury or yield, whereas the use of layered residual herbicides, including IFT, increased Palmer amaranth control compared to those without. Regardless of earlier use of IFT, layby applications were needed for season-long control of Palmer amaranth, entireleaf morningglory, broadleaf signalgrass, and johnsongrass, as evidenced by greater than a 20 percentage point improvement in control of all weeds when a layby application was made. Overall, findings from these studies indicate IFT to be a suitable tool for managing Palmer amaranth and will provide an additional site of action for cotton herbicide programs. Sequential herbicide applications and overlaying residuals were found to be paramount for managing Palmer amaranth throughout the season.

Evaluation of panicle removal methods and crop topping applications as supplemental tools for wild oat (Avena fatua) management

AbstractIncreased frequency and occurrence of herbicide-resistant biotypes heightens the need for alternative wild oat management strategies. This study aimed to exploit the height differential between wild oat and crops by targeting wild oat between panicle emergence and seed shed timing. Two field studies were conducted either in Lacombe, AB, or Lacombe, AB and Saskatoon, SK, from 2015 to 2017. In the first study, we compared panicle removal methods: hand clipping, use of a hedge trimmer, and a selective herbicide crop topping application to a weedy check and an industry standard in-crop herbicide application in wheat. These treatments were tested early (at panicle emergence), late (at initiation of seed shed), or in combination at one location over 3 yr. In the second study, we investigated optimal timing of panicle removal via a hedge trimmer with weekly removals in comparison to a weedy check in wheat and lentil. This study was conducted at two locations, Lacombe, AB, and Saskatoon, SK, over 3 yr. Among all the tested methods, the early crop topping treatment consistently had the largest impact on wild oat density, dockage, seedbank, and subsequent year crop yield. The early (at panicle emergence) or combination of early and late (at initiation of seed shed) treatments tended to reduce wild oat populations the following season the most compared to the late treatments. Subsequent wild oat populations were not influenced by panicle removal timing, but only by crop and location interactions. Panicle removal timing did significantly affect wild oat dockage in the year of treatment, but no consistent optimal timing could be identified. However, the two studies together highlight additional questions to be investigated, as well as the opportunity to manage wild oat seedbank inputs at the panicle emergence stage of the wild oat lifecycle.

Fluopyram as a rescue nematicide for managing sting nematode (Belonolaimus longicaudatus) on commercial strawberry in Florida

The sting nematode (Belonolaimus longicaudatus) is one of the most economically damaging pests of strawberry in Florida. In this study we evaluated in-season application of fluopyram for management of B. longicaudatus populations at nine commercial strawberry farms. In-crop application of fluopyram reduced B. longicaudatus population densities in soil by the end of the growing season in four out of six of the commercial strawberry farms where B. longicaudatus was detected during the growing season. At the four sites, relative suppression of B. longicaudatus by fluopyram ranged from 54 to 96%. Despite significant suppression of B. longicaudatus population densities in soil, in-crop application of fluopyram did not result in greater strawberry plant vigour by the end of the growing season. Overall, in-crop application of fluopyram shows considerable potential to reduce B. longicaudatus populations on strawberry in Florida.

Food, Feed and Environmental Risk Assessment of Glufosinatetolerant Genetically Modified Oilseed Rape T45 for Food and Feed Uses, Import and Processing Under Regulation (EC) No 1829/2003 (Application EFSA/GMO/UK/2005/25)

Food, Feed and Environmental Risk Assessment of Glufosinatetolerant Genetically Modified Oilseed Rape T45 for Food and Feed Uses, Import and Processing Under Regulation (EC) No 1829/2003 (Application EFSA/GMO/UK/2005/25)

Preliminary Environmental Risk Assessment of Genetically Modified Oilseed Rape MON 88302 for Food and Feed Uses, Import and Processing under Regulation (EC) No 1829/2003 (Application EFSA/GMO/BE/2011/101)

Preliminary Environmental Risk Assessment of Genetically Modified Oilseed Rape MON 88302 for Food and Feed Uses, Import and Processing under Regulation (EC) No 1829/2003 (Application EFSA/GMO/BE/2011/101)

Environmental Risk Assessment of Glufosinate-Tolerant Genetically Modified Oilseed Rape T45 for Food and Feed Uses, Import and Processing under Regulation (EC) No 1829/2003 (Application EFSA/GMO/UK/2005/25)

Environmental Risk Assessment of Glufosinate-Tolerant Genetically Modified Oilseed Rape T45 for Food and Feed Uses, Import and Processing under Regulation (EC) No 1829/2003 (Application EFSA/GMO/UK/2005/25)

Environmental Risk Assessment of Glufosinate-Tolerant Genetically Modified Oilseed Rape MS8, RF3 and MS8 x RF3 for Import, Processing and Feed Uses under Directive 2001/18/EC (Notification C/BE/96/01)

Environmental Risk Assessment of Glufosinate-Tolerant Genetically Modified Oilseed Rape MS8, RF3 and MS8 x RF3 for Import, Processing and Feed Uses under Directive 2001/18/EC (Notification C/BE/96/01)

Off-target Movement of DGA and BAPMA Dicamba to Sensitive Soybean

AbstractIt is well established that dicamba can cause severe injury to soybean that is not resistant to dicamba. Dicamba-resistant (DR) cotton became available in 2015, followed by DR soybean in 2016; in late 2016 came the release of new dicamba formulations approved for topical use in cotton and soybeans. Until this approval, use of dicamba was limited to primarily corn, small grains, range and pasture, and eco-fallow acres. Hence, studies were conducted in 2015 and 2016 to examine off-target movement of two dicamba formulations using non-DR soybean as a bio-indicator. Diglycolamine (DGA) andN,N-Bis(3-aminopropyl)methylamine (BAPMA) dicamba were applied simultaneously at 560 g ae ha–1in the center of two side-by-side 8-ha fields to vegetative glufosinate-resistant soybean. On the same day, a rate response experiment was established encompassing nine different dicamba rates of each formulation. Results from the rate response experiment indicate that soybean is equally sensitive to DGA and BAPMA dicamba. In 2015, a rain event occurring 6 to 8 h after application of the large drift trial probably limited off-target movement by incorporating some of the herbicide into the soil. As a result, secondary drift was less in 2015 than in 2016. However, minimal secondary injury (<5%) occurred 12 m farther into DGA dicamba plots in 2015. In 2016, secondary movement was decreased by 72 m when BAPMA dicamba was used compared to DGA dicamba. Appreciable secondary movement of both DGA and BAPMA dicamba is possible following in-crop applications of either formulated product to soybean in early to mid-summer. Additionally, the risk for secondary movement of BAPMA dicamba is slightly less than for DGA dicamba.

Managing glyphosate-resistant common ragweed (Ambrosia artemisiifolia): effect of glyphosate-phenoxy tank mixes on growth, fecundity, and seed viability

Common ragweed is one of the most important weeds in the soybean-producing areas of the United States and Canada. Recently, glyphosate-resistant (GR) biotypes have been reported in 15 states and one Canadian province. Reducing the proliferation of GR common ragweed biotypes is complicated by the high fecundity and complex seed germination behavior exhibited by this species. An experiment was conducted to evaluate the efficacy of late herbicide applications for reducing seed production, seed weight, and seed viability of a GR common ragweed biotype. Herbicide treatments included: water control, glyphosate, 2,4-D, dicamba, 2,4-D plus glyphosate, and dicamba plus glyphosate. Treatments were applied at the appearance of male flower buds (Biologische Bundesanstalt, Bundessortenamt and Chemical industry scale [BBCH] 51) or at the early female flowering stage (BBCH 61 to 63). At BBCH 51, 2,4-D or dicamba applied alone or in a tank mix with glyphosate reduced seed production by an average of 80%. Conversely, seed production following these same treatments applied at BBCH 61 to 63 was not significantly different from when glyphosate was applied alone. At this stage of development, all herbicide treatments reduced seed viability relative to the control; however, treatments containing 2,4-D or dicamba resulted in significantly lower viability than when glyphosate was applied alone. These results suggest that the application of tank mixes containing 2,4-D or dicamba have the potential to limit seed production of GR common ragweed when applied on or before BBCH 51. The development of new technologies that facilitate the in-crop application of tank mixes containing 2,4-D or dicamba may therefore be an effective option for limiting population establishment, seedbank replenishment, and future spread of glyphosate-resistant alleles.

Response of Processing Tomato to Simulated Bromoxynil Drift Followed by In-Crop Metribuzin Application

Simulated drift rates of bromoxynil followed by an in-crop application of metribuzin were applied to processing tomato in eight field studies conducted from 2008 to 2010 in Ridgetown, Ontario, Canada, to determine if a synergistic interaction occurred due to the cumulative herbicide application. A transient synergistic response was observed 7 d after treatment (DAT) when bromoxynil drift rates of 8.5, 17, and 34 g ai ha−1were followed 3 to 5 d later by metribuzin at 250 g ai ha−1. By 28 DAT, visible injury ratings were additive for 8.5, 17, and 34 g ha−1bromoxynil followed by metribuzin treatments. However, when bromoxynil at 68 g ha−1(20% of field rate) was followed by metribuzin, a synergistic interaction was evident and remained through harvest. Based on Colby's equation there was greater visible injury than expected at 7, 14, and 28 DAT when bromoxynil at 68 g ha−1was followed by metribuzin. A corresponding synergistic reduction of plant dry weight and marketable tomato yield, compared with the nontreated control, was identified. Marketable yields were expected to be 65% of the control according to Colby's equation, but observed yield reductions were 49% when bromoxynil at 68 g ha−1was followed by metribuzin. In general, tomato plants sprayed with metribuzin after bromoxynil drift had greater injury than treatments sprayed with bromoxynil alone.

Response of Processing Tomato to Simulated Glyphosate Drift Followed by In-Crop Metribuzin Application

Eight field studies were conducted over a 3-yr period from 2008 to 2010 in Ridgetown, Ontario, Canada, to determine the cumulative stress caused by simulated glyphosate spray drift followed by an in-crop application of metribuzin in processing tomato. As the simulated glyphosate spray drift rate increased so did the degree of injury to the tomatoes. At a simulated spray drift rate of 22.5 g ae ha−1(2.5% of the recommended glyphosate field rate), a 23% decrease in red tomato yield was observed. Yield reductions increased to 88% of the control when 180 g ae ha−1glyphosate (20% of the recommended field rate) was applied. Similarly when simulated spray drift rates were followed 3 to 5 d later with an in-crop application of metribuzin at 250 g ai ha−1, tomato yields decreased by 22 to 85% depending on glyphosate rate applied. A transient synergistic interaction was observed only when 22.5 g ae ha−1glyphosate was followed by metribuzin. The synergistic response was no longer evident by the 28-d injury rating. Herbicide interactions were additive for crop injury, dry weight, fruit counts, and yield when glyphosate spray drift rates of 45, 90, or 180 g ae ha−1were followed by metribuzin.

Site-specific wild oat (Avena fatua L.) management

Beckie, H. J. and Shirriff, S. 2012. Site-specific wild oat ( Avena fatua L.) management. Can. J. Plant Sci. 92: 923–931. Variation in soil properties, such as soil moisture, across a hummocky landscape may influence wild oat emergence and growth. To evaluate wild oat emergence, growth, and management according to landscape position, a study was conducted from 2006 to 2010 in a hummocky field in the semiarid Moist Mixed Grassland ecoregion of Saskatchewan. The hypothesis tested was that wild oat emergence and growth would be greater in lower than upper slope positions under normal or dry early growing season conditions. Three herbicide treatments were imposed on the same plots each year of a 2-yr canola (Brassica napus L.) – wheat (Triticum aestivum L.) sequence: (1) nontreated (weedy) control; (2) herbicide application to upper and lower slope positions (i.e., full or blanket application); and (3) herbicide application to lower slope position only. Slope position affected crop and weed densities before in-crop herbicide application in years with dry spring growing conditions. Site-specific wild oat herbicide application in hummocky fields in semiarid regions may be justified based on results of wild oat control averaged across slope position. In year 2 of the crop sequence (wheat), overall (i.e., lower and upper slope) wild oat control based on density, biomass, and dockage (i.e., seed return) was similar between site-specific and full herbicide treatment in 2 of 3 yr. Because economic thresholds have not been widely adopted by growers in managing wild oat, site-specific treatment in years when conditions warrant may be an appropriate compromise between no application and blanket herbicide application.

Nitrous oxide emissions in response to ESN and urea, herbicide management and canola cultivar in a no-till cropping system

Environmentally Smart Nitrogen (ESN), a type of polymer-coated urea, synchronizes N release with crop demand to increase N use efficiency and potentially reduce N 2O emissions. This study investigated the effects of ESN and weed management on N 2O emissions from soil under a canola ( Brassica napus L.) no-till cropping system. The experiment was conducted from 2005 to 2008 at three sites: Lethbridge, Lacombe, and Beaverlodge, located in southern, central and northern Alberta, Canada. Treatments included a hybrid and an open-pollinated canola cultivar, with ESN and urea applied at 1 and 1.5 times (×) the recommended rate, and herbicide at 50 and 100% of registered in-crop application rates. Canola was grown in rotation with barley ( Hordeum vulgare L.) and both phases of crop rotation were present each year. The N 2O fluxes from soil were measured using vented static chambers at 2-week intervals during the growing season from 2006 to 2008. Except for a few occasions with higher fluxes from urea than ESN earlier in the growing season and higher fluxes from ESN than urea later on, N 2O fluxes were similar among all treatments for all three years and three sites. The N 2O fluxes also varied over the growing season, and peak flux occurred in response to rainfall events. Similarly, cumulative N 2O emissions, expressed as either per land area or per canola seed yield, over the three growing seasons were low (0.15–2.97 kg N ha −1 yr −1 or 0.05–1.19 g N kg −1 seed) for all treatments and sites, and unaffected by weed management or crop variety ( P > 0.05). The N 2O emission across the three sites from ESN averaged 20% lower ( P = 0.040) than from urea although the differences between fertilizer types or application rates were not significant ( P > 0.05) at each site. Elevated N 2O emissions (72% higher; P = 0.028) from 1.5 × ESN (0.83 kg N ha −1 yr −1 or 0.33 g N kg −1 seed) relative to 1 × ESN (0.26 kg N ha −1 yr −1 or 0.16 g N kg −1 seed) were only observed at Beaverlodge while emissions were similar ( P > 0.05) at the other two sites. The higher N 2O emissions at 1.5 × ESN at Beaverlodge were due to excess N accumulation in soil caused by unfavourable weather conditions that reduced canola N uptake and yield. Our results suggest that ESN fertilizer could reduce N 2O emissions in Alberta, Canada, but reductions will depend on rainfall events and canola N utilization.

Evaluation of Legume Cover Crops and Weed Control Programs in Conservation-Tillage, Enhanced Glyphosate-Resistant Cotton

Research was conducted at Marianna, AR, for 2 yr to determine whether hairy vetch and Austrian winter pea cover crops would aid weed management programs in conservation-tilled, enhanced glyphosate-resistant cotton. Both cover crops were easily established and produced rapid growth in early spring, with biomass production of 435 to 491 g m−2by Austrian winter pea and 415 to 438 g m−2by hairy vetch. The effect of cover crops on weed control was short-lived in both years, with herbicide programs being the major determinant of weed control and seed-cotton yield. Averaged over cover crops, seed-cotton yields when the initial in-crop glyphosate application was delayed to the four-node cotton stage were up to 710 kg ha−1less than in a PRE herbicide program. In 1 of 2 yr, seed-cotton yields were greater in PRE-treated plots compared with a program where initial weed management was delayed to the one-leaf stage of cotton. As a result of rapid decay of hairy vetch and Austrian winter pea biomass following cotton planting and the lack of adequate Palmer amaranth, pitted morningglory, and goosegrass control in the absence of herbicides, it appears there may be minimal weed management benefits from the use of hairy vetch and Austrian winter pea in Midsouth cotton production.

Pre-emergence mechanical weed control in field pea (Pisum sativum L.)

Producers who wish to adopt organic or pesticide-free crop production are seeking alternatives to herbicides. A field experiment was conducted at Scott, SK, from 1999 to 2001 to determine the combination of seeding date (early-May, mid-May, and late-May) and weed management system (shallow-seeded untreated, shallow-seeded with pre-emergence tillage, shallow-seeded herbicide, deep-seeded untreated, deep-seeded with pre-emergence tillage, and deep-seeded herbicide) that would optimize yield of field pea grown without the use of herbicides. The shallow and deep seeded pre-emergence tillage treatments were a 2.5-cm seeding depth followed by two sequential harrow passes and a 7.5-cm seeding depth followed by two sequential rod-weeder passes, respectively. None of the weed management systems had a significant effect on field pea density. The herbicide treatments were the only treatments that had a significant effect on weed density as the application timing was more synchronous with weed emergence than were the tillage treatments. The pre-emergence tillage treatments reduced weed biomass when seeding was delayed until mid-May following weed emergence. Deep seeding followed by pre-emergence rod-weeding was more efficacious in reducing weed fresh weight than shallow seeding followed by pre-emergence harrowing; however, they both provided similar yield responses at the mid-May seeding date. Delayed seeding until late May resulted in a 30 to 35% reduction in field pea yield compared with early or mid-May seeding, respectively. Early-seeded field peas followed by an in-crop herbicide application resulted in the highest field pea yields with the best seeding date by pre-emergence tillage combination achieving 81% of these yields. A strategy for field pea producers who choose not to use herbicides would be to delay seeding until some weeds emerge and seed at a 7.5-cm depth followed by two sequential rod-weeding passes prior to crop emergence. Key words: Field pea, seeding date, seed depth, pre-emergence tillage

Simulated mesotrione drift followed by glyphosate, imazethapyr, bentazon or glyphosate plus chlorimuron in soybean

There have been anecdotal accounts of increased crop sensitivity due to herbicide drift followed by an in-crop herbicide. An experiment was conducted from 2005 to 2007 at Elora, Ridgetown, and Woodstock, Ontario, to determine the effects of simulated mesotrione drift followed by in-crop applications of glyphosate, imazethapyr, bentazon and glyphosate plus chlorimuron on glyphosate-resistant soybean [Glycine max (L.) Merr.] visual injury, plant height, plant density, shoot dry weight, and seed yield. As the rate of simulated mesotrione drift increased, there was an increase in soybean injury and a decrease in shoot dry weight, height, and yield. Simulated mesotrione drift followed by bentazon resulted in synergistic responses in injury shortly after application in some environments. This increase in injury was transient, with no synergistic responses in density, shoot dry weight, and yield. In contrast, antagonistic responses were observed when glyphosate, imazethapyr, or glyphosate plus chlorimuron were applied after simulated mesotrione drift in some environments. Further research is required to develop a better understanding of the interactions of drift followed by the application of an in-crop herbicide. Key words: Bentazon, chlorimuron, glyphosate, imazethapyr, mesotrione, synergism

Influence of Glyphosate-Resistant Horseweed (Conyza canadensis) Growth Stage on Response to Glyphosate Applications

Infestations of glyphosate-resistant (GR) horseweed have become widespread in the eastern United States. This biotype is problematic in no-tillage production that relies extensively on glyphosate for weed control. Because horseweed is treated at various stages of growth, a greenhouse study explored rate response of glyphosate-resistant and -susceptible horseweed at three growth stages. GR horseweed was more responsive to glyphosate at the seedling stage than at the large rosette or bolting stages. A field study evaluated GR horseweed response when treated with glyphosate at soybean planting time, POST in-crop (about 45 d after planting), or both at planting and POST in-crop. There was a cumulative effect of the at-planting followed by POST in-crop glyphosate applications. When evaluating single glyphosate applications, the at-planting application was more effective at suppressing GR horseweed than a POST in-crop application. Because glyphosate cannot control GR horseweed, this biotype should be controlled with an herbicide with an alternate mode of action and applied at the most effective timing.

Response of Corn to Simulated Glyphosate Drift Followed by In-Crop Herbicides

Thirteen field experiments were conducted in Illinois, Indiana, Ohio, and Ontario from 2005 to 2007 to determine the effects of simulated glyphosate drift followed by in-crop applications of nicosulfuron/rimsulfuron plus dicamba/diflufenzopyr or foramsulfuron plus bromoxynil plus atrazine on nontransgenic corn injury, height, stand count, shoot dry weight, and yield. Simulated glyphosate drift at 100 and 200 g/ha, resulted in 11 to 61% visual crop injury and a 19 to 45% decrease in corn height. Simulated glyphosate drift at 200 g/ha caused a reduction in shoot dry weight by 46%, stand count by 28% and yield by 49 to 56%. Generally, simulated glyphosate drift followed by the in-crop herbicides resulted in an additive response with respect to visual crop injury, height, stand count, shoot dry weight, and yield.

Validating economic and environmental sustainability of a short-term summer forage legume in dryland wheat cropping systems in south-west Queensland

The present study set out to test the hypothesis through field and simulation studies that the incorporation of short-term summer legumes, particularly annual legume lablab (Lablab purpureus cv. Highworth), in a fallow–wheat cropping system will improve the overall economic and environmental benefits in south-west Queensland. Replicated, large plot experiments were established at five commercial properties by using their machineries, and two smaller plot experiments were established at two intensively researched sites (Roma and St George). A detailed study on various other biennial and perennial summer forage legumes in rotation with wheat and influenced by phosphorus (P) supply (10 and 40 kg P/ha) was also carried out at the two research sites. The other legumes were lucerne (Medicago sativa), butterfly pea (Clitoria ternatea) and burgundy bean (Macroptilium bracteatum). After legumes, spring wheat (Triticum aestivum) was sown into the legume stubble. The annual lablab produced the highest forage yield, whereas germination, establishment and production of other biennial and perennial legumes were poor, particularly in the red soil at St George. At the commercial sites, only lablab–wheat rotations were experimented, with an increased supply of P in subsurface soil (20 kg P/ha). The lablab grown at the commercial sites yielded between 3 and 6 t/ha forage yield over 2–3 month periods, whereas the following wheat crop with no applied fertiliser yielded between 0.5 to 2.5 t/ha. The wheat following lablab yielded 30% less, on average, than the wheat in a fallow plot, and the profitability of wheat following lablab was slightly higher than that of the wheat following fallow because of greater costs associated with fallow management. The profitability of the lablab–wheat phase was determined after accounting for the input costs and additional costs associated with the management of fallow and in-crop herbicide applications for a fallow–wheat system. The economic and environmental benefits of forage lablab and wheat cropping were also assessed through simulations over a long-term climatic pattern by using economic (PreCAPS) and biophysical (Agricultural Production Systems Simulation, APSIM) decision support models. Analysis of the long-term rainfall pattern (70% in summer and 30% in winter) and simulation studies indicated that ~50% time a wheat crop would not be planted or would fail to produce a profitable crop (grain yield less than 1 t/ha) because of less and unreliable rainfall in winter. Whereas forage lablab in summer would produce a profitable crop, with a forage yield of more than 3 t/ha, ~90% times. Only 14 wheat crops (of 26 growing seasons, i.e. 54%) were profitable, compared with 22 forage lablab (of 25 seasons, i.e. 90%). An opportunistic double-cropping of lablab in summer and wheat in winter is also viable and profitable in 50% of the years. Simulation studies also indicated that an opportunistic lablab–wheat cropping can reduce the potential runoff + drainage by more than 40% in the Roma region, leading to improved economic and environmental benefits.