Ellen B. Mallory

Comparison of alternative pest and soil management strategies for Maine potato production systems

Potato acreage and total production in Maine have declined steadily since the 1960s. In 1991, a University of Maine research team established a large-scale, long-term, comparative study of three factors that form the foundation of productive potato cropping systems: soil management, pest management, and variety choice. This study, the Potato Ecosystem Project, included 96 main plots (5.8 ha total) and near-by “component studies.” The project contrasted amended vs. unamended soil management strategies; conventional vs. reduced-input vs. bio-intensive pest management strategies; and disease and stress susceptible vs. tolerant potato varieties. Given recent concerns over resistance to pesticides and increasing costs of agricultural chemical inputs, the reduced-input and bio-intensive pest management systems provided encouraging results. Weed growth was similar in the conventional and reduced-input systems. Colorado potato beetle thresholds were exceeded less often and their densities were lower in the bio-intensive system than in the reduced-input and conventional systems. Lady beetles, which are major aphid predators, were more abundant in the bio-intensive pest management system compared with the reduced-input and conventional systems in 5 of the 6 years. Tuber yield and quality were maintained at a high level in the reduced-input system, although difficulties with plant disease, nutrient and weed management contributed to significantly lower yields in the bio-intensive pest management system. Economic analysis indicated that from 1993 to 1996, the reduced-input system had a greater return over variable cost (avg.

Economic and environmental implications of wheat-crop sequences on organic dairy-farm simulations

973 ha -1 ) than the conventional (avg.

Nitrogen Availability from Compost in High Tunnel Tomato Production

890ha -1 ) and bio-intensive pest management systems (avg.

On-farm produced microbial soil inoculant effects on bread wheat (Triticum aestivum) production

578ha -1 ). The amended soil management system achieved rapid improvements in soil quality: soil organic matter, water stable aggregates, potassium, and soluble inorganic phosphorus contents increased while requirements for synthetic fertilizers were reduced. These improvements in soil quality enhanced late-season crop vigor, canopy duration and tuber quality, and increased yields by 13% and 30% over the unamended system in 1994 and 1995, respectively, but not in 1996. Improved crop vigor in the amended soil management system also benefited weed control efforts by encouraging a more weed-suppressive potato crop. In the biointensive pest management system, in which weeds were controlled mechanically, the amended soil management system had less weed biomass than the unamended soil management system in 1994 and 1995. Conversely, the amended soil management system consistently increased flea beetle populations and, in one of two years, the incidence of Rhizoctonia. The choice of potato variety also affected pest dynamics. Total aphid density (all aphid species considered together) and almost all disease ratings were higher on ‘Superior’ than ‘Atlantic’ potato.

Impacts of soil amendment history on nitrogen availability from manure and fertilizer

Abstract. The market for high-quality organic bread wheat (Triticum aestivum L.) is increasing in New England, USA, providing opportunities for organic dairy farmers to grow this alternative cash crop. Our objective was to determine the sustainability of eight 3-year crop sequences compared with a perennial forage baseline in long-term (25-year), well-managed, medium-sized organic dairy farm simulations. Systems included wheat (spring or winter) preceded by maize (Zea mays L.) silage, a 1-year-old perennial forage grass, or soybean as well as maize silage followed by maize silage or soybean. Farm net return was highest for the entirely grass-based system (US

Potato yield stability under contrasting soil management strategies

742.15 cow–1). Higher winter wheat yields for soybean–wheat–grass resulted in 7% more income from feed sales (

Performance, economics, and adoption of cover crops in Wisconsin cash grain rotations: On-farm trials

1027) than spring wheat. Soybean followed by wheat reduced soil nutrient accumulation by 0.8 kg ha–1 year–1 for phosphorus runoff and leachate losses and for potassium accumulation (–17%); there was also a 4% reduction in water footprint (kg kg–1 fat- and protein-corrected milk). Growing winter wheat provides long-term environmental and economic benefits, although for spring wheat, much of this benefit is lost. Use of maize silage in place of grass, winter or spring wheat, or soybean was less profitable. Most cropping system scenarios were less economically favourable than producing and feeding exclusively grass silage. However, inclusion of soybean increased economic benefits.

Impact of Spring Wheat Planting Density, Row Spacing, and Mechanical Weed Control on Yield, Grain Protein, and Economic Return in Maine

ABSTRACT High yield agricultural systems, such as high tunnel (HT) vegetable production, require a large supply of soil nutrients, especially nitrogen (N). Compost is a common amendment used by HT growers both to supply nutrients and to improve physical and biological soil properties. We examined commercially-available composts and their effects on soil N, plant N uptake, and tomato yield in HT cultivation. In addition, a laboratory study examined N and carbon (C) mineralization from the composts, and the usefulness of compost properties as predictors of compost N mineralization was assessed under field and laboratory conditions. The field study used a randomized complete block design with four replications to compare four compost treatments (all added at the rate of 300 kg total N ha−1) with unamended soil and an inorganic N treatment (110 kg N ha−1). Tomatoes were grown in Monmouth, Maine during the summers of 2013 and 2014. Compost NO3−-N and NH4+-N application rates were significantly correlated with soil NO3−-N and NH4+-N concentrations throughout the growing season. Marketable yield was positively correlated with compost total inorganic N and NO3−-N in both years, and with NH4+-N in 2014. There were no significant differences among composts in percentage of organic N mineralized and no correlations were observed with any measured compost property. In the laboratory study, all compost-amended soils had relatively high rates of CO2 release for the initial few days and then the rates declined. The compost-amended soils mineralized 4%–6% of the compost organic N. This study suggested compost inorganic N content controls N availability to plants in the first year after compost application.

Effects of Profile Depth and Management on the Composition of Labile and Total Soil Organic Matter

The use of microbial soil inoculants in agriculture is of increasing interest among growers and scientists. This study aimed to determine the effects of a commercially available arbuscular mycorrhizal fungus (AMF) inoculant, an on-farm produced AMF inoculant, and an on-farm produced indigenous microbial inoculant on bread wheat (Triticum aestivum L.) AMF colonization, biomass accumulation, nutrient uptake and recovery, and grain yield and protein in a containerized greenhouse experiment and two years of field trials conducted in Maine, USA. The inoculants were compared with respective controls (sterilized inoculants) and the levels of N, P and K were equalized across treatments. Both AMF inoculants enhanced AMF colonization in a greenhouse potting mix containing unsterilized field soil, but only the on-farm produced AMF increased aboveground biomass and phosphorus (P) uptake and recovery. No differences were observed among inoculants and their relative controls in the field. However, the indigenous microbial inoculant (IMO+) increased wheat aboveground biomass, nutrient uptake, nutrient recovery and grain yield when compared with the mycorrhizal inoculants, but no increases were observed when contrasted against its control (IMO − ). Wheat growth enhancements from IMO were likely due to nutrient supply from the compost-based material in which it was produced. Results demonstrate that a mycorrhizal inoculant produced on-farm can increase wheat AMF colonization, aboveground biomass, and P uptake and recovery in a containerized setting. Otherwise differences between inoculants and their relative controls were limited, perhaps due to competition from the native soil microbial community, thus inoculation of field plots cannot be recommended for wheat.