Dryland Systems Research Articles

Water and sediment quality of dry season pools in a dryland river system: the upper Leichhardt River, Queensland, Australia

This article presents the geochemical characteristics and physicochemical properties of water and sediment from twelve semi-permanent, dryland pools in the upper Leichhardt River catchment, north-west Queensland, Australia. The pools were examined to better understand the quality of sediments and temporary waters in a dryland system with a well-established metal contamination problem. Water and sediment sampling was conducted at the beginning of the hydroperiod in May and September 2007. Water samples were analyzed for major solute compositions (Ca, Na, K, Mg, Cl, SO(4), HCO(3)) and water-soluble (operationally defined as the <0.45 μm fraction) metals (Cd, Cu, Pb, Zn). Sediment samples were analyzed for total extractable and bioaccessible metals (As, Cd, Cu, Pb, Zn), elemental composition and grain morphology. At the time of sampling a number of pools contained water and sediment with elevated concentrations, compared to Australian regulatory guidelines, of Cu (maximum: water 28 μg L(-1); sediment 770 mg kg(-1)), Pb (maximum: water 3.4 μg L(-1); sediment 630 mg kg(-1)) and Zn (maximum: water 150 μg L(-1); sediment 780 mg kg(-1)). Concentrations of Cd and As in pools were relatively low and generally within Australian regulatory guideline values. Localized factors, such as the interaction of waters with anthropogenic contaminants from modern and historic mine wastes (i.e. residual smelter and slag materials), exert influence on the quality of pool waters. Although the pools of the upper Leichhardt River catchment are contaminated, they do not appear to be the primary repository of water and sediment associated metals when compared to materials in the remainder channel and floodplain. Nevertheless, a precautionary approach should be adopted to mitigating human exposure to contaminated environments, which might include the installation of appropriate warning signs by local health and environmental authorities.

Assessing Vulnerability to Climate Change in Dryland Livelihood Systems: Conceptual Challenges and Interdisciplinary Solutions

Fraser, E. D. G., A. J. Dougill, K. Hubacek, C. H. Quinn, J. Sendzimir, and M. Termansen. 2011. Assessing vulnerability to climate change in dryland livelihood systems: conceptual challenges and interdisciplinary solutions. Ecology and Society 16(3): 3. https://doi.org/10.5751/ES-03402-160303

Feeding selectivity of introduced hedgehogs Erinaceus europaeus in a dryland habitat, South Island, New Zealand

We describe the diet of introduced European hedgehogs Erinaceus europaeus (Linnaeus, 1758) in a New Zealand dryland system and provide the first quantitative analysis of food selectivity for this species. We also describe and compare the diets of nine hedgehogs and measure dietary overlap between these individuals. The most commonly eaten foods were beetles, including rare native species (in 94% of droppings), earwigs (92%), spiders (25%) and native skinks (14%). Remains of at least three skinks were found in one dropping. Earwigs and darkling beetles (Tenebrionidae) were the most preferred food types, and Hymenoptera and cylindrical bark beetles (Colydiidae) were least preferred. Consumption of most foods mirrored their availability. Most individuals’ diets conformed to the pattern seen at the population scale, with 21–54% of dry faecal mass derived from beetles and 13–39% from earwigs. One animal frequently consumed large amounts of fruit. Dietary overlap between pairs of individuals was high (mean Horn’s index, 0.84). This may be the result of limited opportunities to diversify in a very moisture-limited and low diversity habitat.

Energy consumption in production of grains prevalent in Saveh, Iran.

This paper examines the energy consumption of wheat, barley and maize production in Iran (Saveh area). This study was conducted over 28,400 ha of irrigated wheat, barley and maize fields and 19,300 ha of dry land wheat and barley fields in Saveh, a central city, Iran, in the harvest year of 2003 - 2004. The data was collected from three different sources: questionnaire, literature review and field measurement. Total energy consumption for irrigated wheat, barley and maize were estimated as 51587, 53529 and 72743 MJ/ha, respectively. Also energy consumption for wheat and barley in dry land system were estimated as 12543 and 11935 MJ/ha, respectively. The average operational energy consumption for cultivation of wheat (irrigated), wheat (dry land), barley (irrigated) , barley (dry land) and maize were 36107, 6067, 40498, 6250 and 48632 MJ/ha, respectively. The maximum energy consumed in these productions, for irrigated farming systems and dry land farming system were irrigation and tillage, respectively. Fuel consumption is one of the important input elements, which must be taken under close managerial supervision in order to optimize the amount of energy consumed.

Economically Optimal Compost Rates for Organic Crop Production

Current guidelines for the use of compost in organic agriculture are based on nutrient targets, which represent the conditions needed for maximum yield. Due to the high cost of inputs, however, a maximum‐yield strategy may be far from economically optimal in some organic cropping systems. In this article we formulate a theory of economically optimal rates (EORs) for compost that incorporates the effects on yield in the years after application. When carryover is neglected, it is well known that the slope of the yield response at the EOR equals the fertilizer/crop price ratio. We show that when carry‐over effects are modeled with a decay series, the critical slope is reduced by the sum of the decay series, and this criterion holds for each crop in a rotation. To demonstrate the application of these theoretical results, we used data from a previous study in which the dryland wheat yield response to compost was measured on organic farmland in northern Utah. Since a decay series was not measured, EORs are presented for a range of values of the cumulative carryover, as well as for different compost/wheat price ratios. The EOR for compost sold by one of the region's main composting facilities was predicted to be zero, which highlights the challenging nature of organic fertility management in northern Utah's dryland agriculture. Confidence in the EOR was hindered by our limited understanding of carryover in dryland systems, which should be a priority for future research.

Implications of Climate Change for Agricultural Sector Performance in Africa: Policy Challenges and Research Agenda

The paper analysed how climate change (CC) has shaped African agriculture in the past and how it might impact on African farm economies in the future and what adaptation strategies African farmers have adopted to cope with these changes. The analyses covered all key farming systems and agro-climates of Africa in 11 countries in which data were collected from over 10,000 farm household surveys. Results provided evidence that African agriculture and the welfare of its rural population are vulnerable to CC. The highest risk of future CC damages is associated with specialised crop and livestock farming (mono systems) particularly under dryland conditions in arid and semi-arid regions. This indicates how difficult it is to achieve an African green revolution under the current high reliance on dryland systems (more than 95% of the land) given predicted harsh future climates (warmer and dryer projections) for most of the dryland areas in Africa. It will require substantial public and private investments in expanding irrigation and development of crop varieties and animal breeds that are tolerant to heat, water and low fertility stresses, and in building roads and marketing infrastructures that will improve access to critical inputs (e.g., fertiliser) and output trade. This essentially requires mainstreaming climate sensitivity as an integral component of all agricultural and broader economic development planning and policy design. Although the expected damages are large, many farming systems and communities in Africa face serious limiting conditions which reduce their ability to adapt and hence increase their vulnerability. Among the key factors found to constrain African farmers’ ability to adopt effective adaptation measures are poor access to information, capital, technology and markets. Policies aimed at promoting farm-level adaptation need to emphasise the critical role of farmers’ education; provision of improved climate, production and market information and the means to implement adaptations through affordable credit facilities. Other needed public interventions to help promote adaptation measures and reduce vulnerability include insurance against climate risks to farmers and provision of safety nets.

Conserving and Optimizing Limited Water for Crop Production

Proper soil and crop management systems are critical for sustainable production in semi-arid environments, and there are principles that apply to both dryland (non-irrigated) and limited-irrigation systems. In the non-irrigated environment, crop residue from no-till systems permits more diverse crop rotations with less frequent fallow, which leads to increased precipitation-use efficiency. Soil improvements from no-till systems include decreased soil erosion, increased soil organic matter, improved soil structure, and increased infiltration rate. These soil improvements create a positive feedback loop by making more water available to the crop, increasing yields, and returning more crop residues to the soil. In the Great Plains of the United States, we have found that annualized grain production from no-till systems with less frequent fallow can be increased by 75% with an increase in economic return from 13% to 36% compared with the traditional wheat-fallow cropping system. There is also a need to increase water productivity for irrigated crop production because of competition for water by municipal and industrial users, drought, and declining groundwater supplies. The adoption of cropping systems that use less water and insure economic sustainability must be developed. We have found that limited-irrigation practices that time irrigations with critical growth stages can reduce water use of corn by 50% while reducing yields by only 30%. Alfalfa was found to have great potential for limited irrigation because of its natural drought tolerance and perennial growth habit. Many of the principles of water-conservation practices identified in the United States are adaptable to India's conditions. Soil and crop management systems that use less water and that are sustainable and economically viable in India's limited water environment must be developed.

Land degradation in drylands: Interactions among hydrologic–aeolian erosion and vegetation dynamics

Land degradation in drylands is one of the major environmental issues of the 21st century particularly due to its impact on world food security and environmental quality. Climate change, shifts in vegetation composition, accelerated soil erosion processes, and disturbances have rendered these landscapes susceptible to rapid degradation that has important feedbacks on regional climate and desertification. Even though the role of hydrologic–aeolian erosion and vegetation dynamic processes in accelerating land degradation is well recognized, most studies have concentrated only on the role of one or two of these components, and not on the interactions among all three. Drawing on relevant published studies, here we review recent contributions to the study of biotic and abiotic drivers of dryland degradation and we propose a more holistic perspective of the interactions between wind and water erosion processes in dryland systems, how these processes affect vegetation patterns and how vegetation patterns, in turn, affect these processes. Notably, changing climate and land use have resulted in rapid vegetation shifts, which alter the rates and patterns of soil erosion in dryland systems. With the predicted increase in aridity and an increase in the frequency of droughts in drylands around the world, there could be an increasing dominance of abiotic controls of land degradation, in particular hydrologic and aeolian soil erosion processes. Further, changes in climate may alter the relative importance of wind versus water erosion in dryland ecosystems. Therefore acquiring a more holistic perspective of the interactions among hydrologic–aeolian erosion and vegetation dynamic processes is fundamental to quantifying and modeling land degradation processes in drylands in changing climate, disturbance regimes and management scenarios.

Opportunities and constraints for intensive agriculture in the Hawaiian archipelago prior to European contact

Intensive agricultural systems interact strongly and reciprocally with features of the lands they occupy, and with features of the societies that they support. We modeled the distribution of two forms of pre-European contact intensive agriculture – irrigated pondfields and rain-fed dryland systems – across the Hawaiian archipelago using a GIS approach based on climate, hydrology, topography, substrate age, and soil fertility. Model results closely match the archaeological evidence in defined locations. On a broader scale, we calculate that the youngest island, Hawai'i, could have supported 572 km 2 of intensive agriculture, 97% as rain-fed dryland field systems, while Kaua'i, the oldest island, could have supported 58 km 2, all as irrigated wetland systems. Irrigated systems have higher, more reliable yields and lower labor requirements than rain-fed dryland systems, so the total potential yield from Kaua'i (∼49k metric tons) was almost half that of Hawai'i (∼97k metric tons), although Kaua'i systems required only ∼0.05 of the agricultural labor (∼8400 workers, versus ∼165,000 on Hawai'i) to produce the crops. We conclude that environmental constraints to intensive agriculture across the archipelago created asymmetric production efficiencies, and therefore varying potentials for agricultural surplus. The implications both for the emergence of complex sociopolitical formations and for anthropogenic transformation of Hawaiian ecosystems are substantial.

Seeking simultaneous improvements in farm profit and natural resource indicators: a modelling analysis

Natural resource indicators are used by catchment management organisations as targets for land use management. However, the nature of the trade-off function between natural resource management (NRM) outcomes and whole-farm profit is ill-defined, and varies between regions and according to the particular NRM indicator considered. Defining this function will assist catchment management organisations and farmers to evaluate the achievability of particular targets, and help determine the size of economic incentives required to offset any expected loss in farm profit associated with meeting targets. We addressed this issue by modelling representative farm businesses in two mixed farming regions (southern New South Wales and the central wheatbelt of Western Australia). The Agricultural Production Systems Simulator (APSIM) and GRAZPLAN farming systems models were linked and used to generate values of four NRM indicators (water leakage, nitrate leaching, groundcover and soil organic carbon change) for a wide range of crop–pasture rotations. The NRM indicator values were then incorporated into the Model of an Integrated Dryland System (MIDAS) whole-farm economic model to define the relationship with farm profit and farm cropping percentage. For some circumstances and indicators, the resulting trade-off functions were relatively flat; a wide range of enterprise mixes can lead to the same NRM outcomes but significant gains in the indicators may not be possible using current rotation options. For others, significant improvements could be achieved but at a substantial loss in whole-farm profit (through the selection of less profitable rotations). There were also examples where simultaneous gains in indicators and farm profit were possible. This analysis demonstrates an approach by which biophysical simulation models of the farming system can be linked to linear-programming representations of farming enterprises, and provides a method for deriving relationships between NRM targets and economic performance.

Does long-term center-pivot irrigation increase soil carbon stocks in semi-arid agro-ecosystems?

This study was conducted to determine the effect of center-pivot irrigation management on soil organic carbon and soil inorganic carbon stocks in semi-arid agroecosystems. We sampled two locations in the Central Great Plains, USA: an area near Imperial, Nebraska and a more arid area near Otis, Colorado. At both locations, three different agroecosystems were sampled: a non-cultivated native grassland (NG), a center-pivot irrigated (CP) and an adjacent dryland (DL) cultivated system. All sampled soils were classified as Aridic, Pachic or Calcidic Argiustoll. Soil organic (SOC) and inorganic (SIC) carbon was analyzed at 0–5, 5–20, 20–50 and 50–75 cm depths. Although significantly greater SOC stocks were found in the surface (0–20 cm) soil layers of CP compared to DL systems at both locations, when the entire 0–75 profile was considered, irrigation significantly increased SOC only at the Imperial site (on average 7626 g m − 2 versus 6637 g m − 2 at Imperial and 6769 g m − 2 versus 5698 g m − 2 at Otis). Soil inorganic C was significantly greater in the cultivated versus the grassland soils, but did not differ between dryland and irrigated management systems. Over the entire profile, differences in SIC at depth were more important than the changes of SOC storage by irrigation management in the 0–20 cm depth. Further, though highly variable, SIC accounted for nearly 50% of the total soil C storage in the cultivated systems at Otis and 30% at Imperial. Large proportions of SIC in these cultivated semi-arid lands are most likely due to cultivation-induced changes in soil properties, water regime and carbonate-forming ion concentrations. These factors must be considered to accurately assess management-induced effects on soil carbon.

Evaporative isotope enrichment as a constraint on reach water balance along a dryland river

Deuterium and oxygen-18 enrichment in river water during its transit across dryland region is found to occur systematically along evaporation lines with slopes of close to 4 in 2H–18O space, largely consistent with trends predicted by the Craig–Gordon model for an open-water dominated evaporating system. This, in combination with reach balance assessments and derived runoff ratios, strongly suggests that the enrichment signal and its variability in the Barwon–Darling river, Southeastern Australia is acquired during the process of evaporation from the river channel itself, as enhanced by the presence of abundant weirs, dams and other storages, rather than reflecting inherited enrichment signals from soil water evaporation in the watershed. Using a steady-state isotope mass balance analysis based on monthly 18O and 2H, we use the isotopic evolution of river water to re-construct a perspective of net exchange between the river and its contributing area along eight reaches of the river during a drought period from July 2002 to December 2003, including the duration of a minor flow event. The resulting scenario, which uses a combination of climatological averages and available real-time meteorological data, should be viewed as a preliminary test of the application rather than as a definitive inventory of reach water balance. As expected for a flood-driven dryland system, considerable temporal variability in exchange is predicted. While requiring additional real-time isotopic data for operational use, the method demonstrates potential as a non-invasive tool for detecting and quantifying water diversions, one that can be easily incorporated within existing water quality monitoring activities.

Genetic Opportunities to Improve Cereal Root Systems for Dryland Agriculture

Understanding the major limitations to root growth is very important if we are to maximize water and nutrient use and increase yields. Limitations may be insufficient rooting depth, root diseases, nutrient deficiencies, toxicities and soil hardness. An understanding of these limitations will lead to more precisely identifying traits for which to select and breed. Examples of successfully overcoming limiting factors to improve crop performance by breeding and selection are given for cereal cyst nematodes in wheat, soil acidity and salinity. The importance of altered crop management practices to reduce limitations is also stressed. These have resulted in a more effective and healthier root system, which results in more water use and greater yields. Opportunities to genetically increase the size of the root system in dryland systems where water and nutrients are not all used by the crop are given.

Spatial pattern effect on corn (Zea mays) weeds competition in the humid Pampas of Argentina

The objectives of this study were to determine the effect of spatial pattern on corn above- and below-ground biomass, grain yield, weed above-ground biomass and soil water and photosynthetically active radiation (PAR) dynamics. Field studies were conducted in 2003 and 2004. Three corn hybrids with two spatial pattern (square and rectangular) under weed-free and weedy conditions were tested. Corn grain yield was greater in the square than in the rectangular pattern. This increase was related to better resources use while reducing the competition from weeds. Early in the growing season, there was greater moisture content in the intrarow at square pattern while a lower soil water content was observed at maturity. Conversely, the square pattern registered lower soil water content during the whole corn growing season in the interrow. This soil water profile was an outcome of the uniform corn below-ground biomass distribution. A greater PAR interception with a lower weed above-ground dry matter was obtained in square plant arrangement. The use of uniform spatial pattern appeared as an interesting alternative to increase both the grain yield potential and the corn suppressive ability against weeds in dry-land Argentinean production systems.

Chemical and biochemical properties of a clay soil under dryland agriculture system as affected by organic fertilization

Understanding of microbial processes in soil is important for the management of farming systems, particularly those that imply organic inputs of nutrients. In this work the effect of consecutive addition of two mature composts (vegetal and animal compost) at rates of 30 tm ha −1 over a 4-year period under a dryland system on the chemical and biochemical properties of a clay soil (Chromic Haploxeret) was investigated and compared to that of an inorganic fertilization. Soil chemical and biological status was evaluated by measuring the total organic carbon (TOC), humic acids, Kjeldahl-N, bicarbonate-extractable P (Olsen-P), ammonium acetate extractable-K (AAE-K), microbial biomass carbon (Cmic), enzymatic activities (dehydrogenase, protease, glucosidase, alkaline phosphatase) and Cmic/TOC ratio. At the end of the study, soils fertilised with composts showed increases in quantity (TOC) and quality (humic acids) of organic matter compared to inorganically fertilised soil. The nutrient content (Olsen-P and Kjeldahl-N) also showed an increase in the plots fertilised with composts. From the fourth crop cycle the plots fertilised with compost showed more clearly the increase in microbial biomass and enzymatic activities, which can have been related both with leguminous pre-crop and with the organic fertilization. In general, under a dryland system, an improvement of soil fertility was achieved in organically fertilised soils, confirming the positive effect of organic fertilization.

ARBUSCULAR MYCORRHIZAL FUNGI DYNAMICS IN CONTRASTING CROPPING SYSTEMS ON VERTISOL AND REGOSOL SOILS OF LOMBOK, INDONESIA

Arbuscular mycorrhizal fungi (AMF) may have a major role in phosphorus nutrition of crops in Lombok, where fertilizer use is low. As a start to understanding this role, AMF dynamics were monitored from the 1999 non-rice season to the end of the 1999/2000 rice season at 32 sites including dryland systems with no rice, upland rice and flooded systems with one or two rice crops per year in the rotation. Over all four systems, root colonization was greater in vertisol (22.3 % of roots) than in regosol (9.5 %) soil, possibly due to lower Bray-1 P content of the vertisol (6.2 v. 13.7 mg kg−1). Colonization was poor in flooded rice (3.1–5.1 %); at the same sampling times it was better in upland rice (10.6–13.4 %) and in non-rice crops growing in dryland systems (13.8–17.0 %). Therefore, the low colonization in flooded rice appeared to be the result of flooding, rather than the rice itself. Flooding also reduced transparent spore numbers, but sufficient inoculum appeared to survive flooding for plants in the following non-rice season to be well colonized (19–33 %) regardless of system. These non-flooded crops appear to replenish depleted AMF propagules.

Architecture of pre-vegetation sandy-braided perennial and ephemeral river deposits in the Paleoproterozoic Athabasca Group, northern Saskatchewan, Canada as indicators of Precambrian fluvial style

The Late Paleoproterozoic Athabasca Basin contains more than 1.5 km of predominantly sandy strata, most of which are of braided fluvial origin. In the eastern part of the basin, at McClean Lake, sandstones and minor conglomerates of the Read Formation at the base of the succession are preserved within a steep-walled valley system. They consist predominantly of meter-scale sheet elements, characterized by massive and flat-laminated fine- to very coarse-grained sandstone with minor discontinuous cobble and boulder conglomerate along lower set boundaries. These are interpreted as sheet-flood and stream-flood deposits of a terminal dry-land system, deposited in an arid climatic setting. Analysis of closely spaced drill-core indicates that late stage run-off was confined to small shallow channels, typically only a few tens of meters wide and a few meters deep. Overlying strata of the Bird Member of the Manitou Falls Formation are predominantly coarse- to very coarse-grained sandstones with abundant small-scale cross-stratification and minor granule and small pebble conglomerate. At McClean Lake, these appear to have been deposited as sheet-elements by semi-ephemeral to perennial braided rivers under more humid conditions. At Key Lake, 160 km to the southwest, architectural analysis of a 184 m wide section indicates that at least part of the Bird Member was deposited in deeper, sandy-braided rivers characterized by seasonally varied flow. The closest modern analogue is the South Saskatchewan River, in which large simple flow-transverse bedforms become exposed and dissected during falling stage, and act as nuclei for sand-flat development. The presence of numerous low-relief 4th order surfaces suggests continued reworking of bar-tops during rising stage. The incremental character of downstream accretionary elements suggests periodic migration of barforms during peak-flood stages, separated by periods of low flow. This indicates similarities with modern perennial braided systems, and is counter to the idea that all pre-Devonian fluvial systems should consist of stacked sheets formed by individual flood events. Thin gravel layers accumulated as lags on fourth order surfaces, with discontinuous mud layers suggesting deposition within temporary ponds in channel thalwegs after major floods. Strata in overlying units indicate a return to semi-perennial conditions.

Ecosystem science and human–environment interactions in the Hawaiian archipelago

Summary Tansley's ecosystem concept remains a vital framework for ecological research in part because the approach facilitates interdisciplinary analyses of ecological systems. Features of the Hawaiian Islands – particularly the nearly orthogonal variation in many of the factors that control variation among ecosystems elsewhere – make the archipelago a useful model system for interdisciplinary research designed to understand fundamental controls on the state and dynamics of ecosystems, and their consequences for human societies. Analyses of rain forest sites arrayed on a substrate age gradient from c. 300 years to over 4 million years across the Hawaiian archipelago demonstrate that the sources of calcium and other essential cations shift from &gt; 80% rock‐derived in young sites to &gt; 80% derived from marine aerosol on substrates older than 100 000 years. Rock‐derived phosphorus is retained longer within ecosystems, but eventually long‐distance transport of continental dust from Asia becomes the most important source of phosphorus. A biogeochemical feedback from low nutrient availability to efficient resource use by trees to slow decomposition and nutrient regeneration accentuates the geochemically driven pattern of low phosphorus availability and phosphorus limitation to net primary productivity in the oldest site. Variations in ecosystem biogeochemistry across the archipelago shaped the development and sustainability of Polynesian agricultural systems in the millennium between their discovery of Hawai’i and contact by Europeans. Irrigated pondfields were largely confined to stream valleys on the older islands, while rain‐fed dryland systems occupied a narrow zone of fertile, well‐watered soils on the younger islands. The ecosystem approach often represents the most appropriate level of organization for analyses of human influences on ecological systems; it can play a central role in the design and analysis of alternative agricultural, industrial and residential systems that could reduce the human footprint on the Earth.

Associations between earliness, Ascochyta response, and grain yield in chickpea

Evidence from an array of dryland systems suggests that chickpea (Cicer arietinum L.) grain yield could be improved through better phenological adaptation. However, information on the relationship between phenology and Ascochyta response genes, and their possible interaction with biomass and grain yield, is missing. Accordingly, the aim of the present study was to determine the associations between the above factors and biomass and grain yield in chickpea. To that end, standard Israeli cultivars and advanced generation bulked progeny from the cv. Hadas × ICC5810 cross were used. Hadas is a late-flowering, high-yielding Israeli kabuli (0.45 g/seed) cultivar with moderate field resistance to Ascochyta blight, whereas ICC5810 is a day-neutral desi (0.15 g/seed) genotype with a strong temperature response, from India. Higher yields were observed among the late-flowering bulks of the Hadas × ICC5810 progeny. No relationship between the Ascochyta response and biomass and grain yield was observed. No interaction between the phenology and Ascochyta response grouping on biomass and grain yield was observed. The results demonstrate the feasibility of combining Ascochyta resistance with earlier flowering and its potential to improve chickpea adaptation to dryland systems.

Chemical Weed Control in Dryland and Irrigated Chickpea1

Field studies were conducted in 2003 and 2004 near Scottsbluff and Sidney, NE, to identify efficacious chemical weed-control options for irrigated and dryland chickpea production. Weed control had a greater relative effect on chickpea yield in the irrigated system than the dryland system, with yield from the hand-weeded check exceeding the nontreated check by 1,500% in the irrigated system and 87% in the dryland system. Imazethapyr, applied preemergence at the rate of 0.053 kg ai/ha, reduced plant height, delayed plant maturity, and caused leaf chlorosis. At Scottsbluff, preplant-incorporated ethalfluralin caused significant crop injury in 2003, but the ethalfluralin treatment also maintained weed densities 4 wk after crop emergence that were not significantly different than the hand-weeded check at both locations in 2003 and 2004. Treatments containing sulfentrazone provided a similar level of weed control but without any evidence of crop injury. Pendimethalin and pendimethalin + dimethenamid-P applied p...