John Luna

Bio: John Luna is an academic researcher from Oregon State University. The author has contributed to research in topics: Cover crop & Tillage. The author has an hindex of 10, co-authored 19 publications receiving 760 citations.

Conservation tillage for organic agriculture: Evolution toward hybrid systems in the western USA

Abstract: Organic farming has been historically dependent on conventional tillage operations to convert perennial pasture leys to annual crop rotations, incorporate crop residues, compost and cover crops, as well as to mechanically kill existing vegetation. Conventional tillage, however, has long been known to lead to soil degradation and erosion. A recently developed no-till organic production system that uses a roller–crimper technology to mechanically kill cover crops was evaluated in two states in the western United States. In Washington, pumpkins (Cucurbita spp.) grown in a no-till roller–crimper (NT-RC) system produced yields 80% of conventional tillage, but with fewer weeds. However, in California on-farm research trials in organic cotton (Gossypium barbadense L.), tomato (Lycopersicon esculentum Mill.), eggplant (Solanum melongena L.) and cowpea (Vigna unguiculata (L.) Walp.), the no-till system produced virtual crop failure, or yields less than 20% of the standard production method. The major problems associated with rolled cover crops in California included reduced crop seedling emergence, planter impediment with excessive residue, lack of moisture and delay in transplanting of vegetable crops due to continued growth of cover crops, in-season crop competition from cover crop regrowth and impracticability of using cultivators. Further, excessive dry residue during summer in California can present the risk of fire. In both California and Oregon, considerable success has been demonstrated with zone tillage (strip tillage) in conventionally produced field and vegetable crops. In a replicated Oregon trial, the organic strip tillage treatment produced 85% of the broccoli (Brassica oleracea L.) yield compared to a conventional tillage treatment. Our studies suggest that the zone tillage concept may offer opportunities to overcome many of the agronomic challenges facing no-till.

Cover crop contributions to N supply and water conservation in corn production

Abstract: Winter annual legume cover crops can reduce nitrogen (N) fertilizer requirements and provide a water-conserving mulch to a subsequent crop. A two-year study was designed to test cover crops of rye (Secale cereale L.), hairy vetch (Vicia villosa Roth), and big/lower vetch (Vicia grandiflora Scopoli) for their ability to produce N and to conserve soil water for a succeeding corn (Zea mays L.) crop. We measured the cover crops' biomass, N yield, carbon (C) to N ratio, and influence on a subsequent corn crop grown under two tillage regimes (disk tillage or no-till). Nitrogen content in cover crop biomass at time of corn planting ranged from 37 to 187 kg/ha. Pure stands of hairy vetch and a mixture of hairy vetch plus bigflower vetch had generally higher N yields, and rye was lowest. Rye growing in association with hairy vetch had lower C:N ratios than rye growing alone. Legume C:N ratios remained generally unchanged from earlier (disked) to later (herbicide) kill dates, but total N and biomass typically increased in the last 2 to 3 weeks before corn planting. Soil water retention was affected by tillage in some cases; no-till was superior to disk incorporation in each case where there was a tillage effect. Cover crops with greater biomass resulted in greater soil water retention. Among cover crops, uptake ofNby corn was greater from hairy vetch or hairy vetch plus bigflower vetch mixture. Biological immobilization of N appeared to be reducing N uptake by corn grown in rye residues. Corn in nonlegume plots fertilized with 140 or 210 kg N/ha took up more N than corn following legumes, but there was no corresponding yield increase. Corn biomass yields following the cover crops ranged from 8.6 to 18.0 Mg/ha with no additional fertilizer N. In the second year of the study, average corn yields following hairy vetch (15.3 Mg/ha) or hairy-bigflower vetch mixtures (16.4 Mg/ha) were not statistically different from corn yields produced by a 140 kg N/ha fertilizer rate (17.4 Mg/ha). These results suggest N from a legume cover crop can replace or substantially reduce fertilizer N requirements in corn production systems in the Appalachian region.

Weed Ecology and Nonchemical Management under Strip-Tillage: Implications for Northern U.S. Vegetable Cropping Systems

Abstract: In northern U.S. vegetable cropping systems, attempts at no-till (NT) production have generally failed because of poor crop establishment and delayed crop maturity. Strip tillage (ST) minimizes these problems by targeting tillage to the zone where crops are planted while maintaining untilled zones between crop rows, which foster improvements in soil quality. ST has been shown to maintain crop yields while reducing energy use and protecting soils in vegetable crops, including sweet corn, winter squash, snap bean, carrot, and cole crops. Despite potential benefits of ST, weed management remains an important obstacle to widespread adoption. Increased adoption of ST in cropping systems for which effective, low-cost herbicides are either limited (e.g., most vegetable crops) or prohibited (e.g., organic systems) will require integration of multiple cultural, biological, and mechanical approaches targeting weak points in weed life cycles. Weed population dynamics under ST are more complex than under eit...

Strip Tillage for Sweet Corn Production: Yield and Economic Return

Abstract: Two strip tillage systems for sweet corn production were compared to conven- tional tillage systems in western Oregon. A power take-off rotary tiller configured to till six rows per pass was used in 1997 and 1998; a shanWcoulter strip tillage machine was used in 1999 and 2000. A paired t test experimental design was used in field-scale, on-farm research with eight replications in 1997-98 and 12 replications in 1999-2000. Sweet corn was harvested using the participating growers' corn pickers and yield was determined. A subset of the participating growers recorded types of machinery and labor for tillage operations and total costs were computed for each tillage system. The rotary strip tillage system produced 900 kgha-' greater corn yields (P = 0.11) than conventional tillage. The shankkoulter strip tillage system produced yields comparable to conventional tillage (P = 0.95). The rotary strip tillage system reduced total tillage costs by an average of $38.50/ha compared to conventional tillage (P = 0.03) and reduced machinery operating time by 0.59 hsha-' (P = 0.01). The shankkoulter strip tillage system reduced tillage costs by $36.50/ha compared to conventional tillage (P = 0.003) and reduced machinery operating time by 0.47 h.ha-'(P = 0.001). Slugs damaged corn in several strip tillage fields requiring the use of slug bait to prevent economic damage. Herbicides used in conventional tillage systems were generally effective in the strip tillage systems. Mechanical cultivation with standard cultivating equipment was more difficult in some of the strip tillage fields with heavy cover crop residue.

Landscape perspectives on agricultural intensification and biodiversity – ecosystem service management

Abstract: Understanding the negative and positive effects of agricultural land use for the conservation of biodiversity, and its relation to ecosystem services, needs a landscape perspective. Agriculture can contribute to the conservation of high-diversity systems, which may provide important ecosystem services such as pollination and biological control via complementarity and sampling effects. Land-use management is often focused on few species and local processes, but in dynamic, agricultural landscapes, only a diversity of insurance species may guarantee resilience (the capacity to reorganize after disturbance). Interacting species experience their surrounding landscape at different spatial scales, which influences trophic interactions. Structurally complex landscapes enhance local diversity in agroecosystems, which may compensate for local high-intensity management. Organisms with high-dispersal abilities appear to drive these biodiversity patterns and ecosystem services, because of their recolonization ability and larger resources experienced. Agri-environment schemes (incentives for farmers to benefit the environment) need to broaden their perspective and to take the different responses to schemes in simple (high impact) and complex (low impact) agricultural landscapes into account. In simple landscapes, local allocation of habitat is more important than in complex landscapes, which are in total at risk. However, little knowledge of the relative importance of local and landscape management for biodiversity and its relation to ecosystem services make reliable recommendations difficult.

REVIEWS AND SYNTHESES Landscape perspectives on agricultural intensification and biodiversity - ecosystem service management

Abstract: Understanding the negative and positive effects of agricultural land use for the conservation of biodiversity, and its relation to ecosystem services, needs a landscape perspective. Agriculture can contribute to the conservation of high-diversity systems, which may provide important ecosystem services such as pollination and biological control via complementarity and sampling effects. Land-use management is often focused on few species and local processes, but in dynamic, agricultural landscapes, only a diversity of insurance species may guarantee resilience (the capacity to reorganize after disturbance). Interacting species experience their surrounding landscape at different spatial scales, which influences trophic interactions. Structurally complex landscapes enhance local diversity in agroecosystems, which may compensate for local highintensity management. Organisms with high-dispersal abilities appear to drive these biodiversity patterns and ecosystem services, because of their recolonization ability and larger resources experienced. Agri-environment schemes (incentives for farmers to benefit the environment) need to broaden their perspective and to take the different responses to schemes in simple (high impact) and complex (low impact) agricultural landscapes into account. In simple landscapes, local allocation of habitat is more important than in complex landscapes, which are in total at risk. However, little knowledge of the relative importance of local and landscape management for biodiversity and its relation to ecosystem services make reliable recommendations difficult.

Sustainable pest regulation in agricultural landscapes: a review on landscape composition, biodiversity and natural pest control

Abstract: Agricultural intensification has resulted in a simplification of agricultural landscapes by the expansion of agricultural land, enlargement of field size and removal of non-crop habitat. These changes are considered to be an important cause of the rapid decline in farmland biodiversity, with the remaining biodiversity concentrated in field edges and non-crop habitats. The simplification of landscape composition and the decline of biodiversity may affect the functioning of natural pest control because non-crop habitats provide requisites for a broad spectrum of natural enemies, and the exchange of natural enemies between crop and non-crop habitats is likely to be diminished in landscapes dominated by arable cropland. In this review, we test the hypothesis that natural pest control is enhanced in complex patchy landscapes with a high proportion of non-crop habitats as compared to simple large-scale landscapes with little associated non-crop habitat. In 74% and 45% of the studies reviewed, respectively, natural enemy populations were higher and pest pressure lower in complex landscapes versus simple landscapes. Landscape-driven pest suppression may result in lower crop injury, although this has rarely been documented. Enhanced natural enemy activity was associated with herbaceous habitats in 80% of the cases (e.g. fallows, field margins), and somewhat less often with wooded habitats (71%) and landscape patchiness (70%). The similar contributions of these landscape factors suggest that all are equally important in enhancing natural enemy populations. We conclude that diversified landscapes hold most potential for the conservation of biodiversity and sustaining the pest control function.

Resilience in Agriculture through Crop Diversification: Adaptive Management for Environmental Change

Abstract: Recognition that climate change could have negative consequences for agricultural production has generated a desire to build resilience into agricultural systems. One rational and cost-effective method may be the implementation of increased agricultural crop diversification. Crop diversification can improve resilience in a variety of ways: by engendering a greater ability to suppress pest outbreaks and dampen pathogen transmission, which may worsen under future climate scenarios, as well as by buffering crop production from the effects of greater climate variability and extreme events. Such benefits point toward the obvious value of adopting crop diversification to improve resilience, yet adoption has been slow. Economic incentives encouraging production of a select few crops, the push for biotechnology strategies, and the belief that monocultures are more productive than diversified systems have been hindrances in promoting this strategy. However, crop diversification can be implemented in a variety of f...

Using winter cover crops to improve soil and water quality

Abstract: This article reviews literature about the impacts of cover crops in cropping systems that affect soil and water quality and presents limited new information to help fill knowledge gaps. Cover crops grow during periods when the soil might otherwise be fallow. While actively growing, cover crops increase solar energy harvest and carbon flux into the soil, providing food for soil macro and microrganisms, while simultaneously increasing evapotranspiration from the soil. Cover crops reduce sediment production from cropland by intercepting the kinetic energy of rainfall and by reducing the amount and velocity of runoff. Cover crops increase soil quality by improving biological, chemical and physical properties including: organic carbon content, cation exchange capacity, aggregate stability, and water infiltrability. Legume cover crops contribute a nitrogen (N) to subsequent crops. Other cover crops, especially grasses and brassicas, are better at scavenging residual N before it can leach. Because growth of thes...