Curt R. Rom

Land use effects on near-surface soil arsenic in the Ozark highlands.

In the early 1900s, northwest Arkansas was the leading apple (Malus sylvestris Mill.)-producing region in the United States. To maximize yields and quality, apple producers used heavy doses of lead (Pb) arsenate at the time to control agricultural pests, particularly the codling moth (Cydia [Laspeyresia] pomonella). Northwest Arkansas is a region underlain by karst geology, specifically fractured limestone and dolomitic bedrock, which creates the potential for rapid downward transport of surface contaminants, such as arsenic (As) from past Pb arsenate usage in the region, to the groundwater. Northwest Arkansas is also presently one of the most rapidly expanding regions in the United States in terms of urbanization and population. Thus, it is critical that high-quality surface and groundwater resources are maintained as potable water sources. The objective of this study was to evaluate the effect of land use (i.e., historic apple orchard, broiler litter-amended pasture, historic orchard-followed-by-broiler-litter-amended pasture, andnonorchard/nonlittered land use) and soil depth (i.e., 0-2, 2-4, and 4-8 cm) on acid-recoverable soil As, Pb, and phosphorus. Soil As concentrations were lowest in the 0- to 2- and/or 2- to 4-cm depth and increased with depth in all land uses, expect for the litter-only pastureland, in which soil As concentrations did not differ among soil depths. Soil Pb concentrations also increased with depth, but only in the orchard-followed-by-litter-amended pasture. Soil As and Pb concentrations were at least numerically greater in all soil depths in the orchard-followed-by-litter-amended pasture than in all other land use/soil depth combinations. Soil phosphorus concentrations were greater at all depths in the land uses that received broiler litter than in those land uses that did not and decreased with depth in all land uses. The results of this study indicate that historic Pb arsenate usage seems to be more responsible for elevated soil As concentrations than even decades of annual land application of As-containing broiler litter to pasturelands that had neverreceived Pb arsenate applications for pest control during apple production.

Feeding damage of Japanese beetle (Col.: Scarabaeidae) on 16 field‐grown birch (Betula L.) genotypes

Feeding damage by Japanese beetle (Popillia japonica Newman) was evaluated on 16 field‐grown birch genotypes (Betula L.) under two irrigation regimes at Fayetteville, AR in 2003, 2004 and 2005. Percentage of total leaf area skeletonized by Japanese beetle was visually estimated, and leaf damage was rated as no damage, low damage, moderate or severe damage based on the percentage of leaf skeletonization. The average percentage of leaf skeletonization on all birch trees by Japanese beetles was 32% in 2003, 27% in 2004 and 25% in 2005. In 2005, well‐watered trees had a higher percentage of leaf skeletonization than water‐stressed trees. Betula utilis var. jacquemontii and Betula papyrifera‘Uenci’, rated as severe damage in all 3 years, were estimated to have the highest percentage of leaf skeletonization followed by B. papyrifera, which was rated as moderate‐to‐severe damage. Betula maximowicziana, Betula nigra‘Cully’, B. papyrifera‘Renci’, and Betula platyphylla‘Fargo’ were rated as low‐to‐moderate damage. Betula pendula‘Laciniata’ had nearly no damage from Japanese beetle in all 3 years. The other birch genotypes were rated as low damage during the 3‐year period.

Reproduction of Mm.106 Rootstocks Propagated by Stooling as Affected by Organic Sources

Six organic sources of nutrients including commercial organic fertilizer (CF), poultry litter (PL), green compost (GC), wood chips (WC), shredded paper (SP), grass clippings (GR), and extracts from water (NF, as a control) were investigated under controlled conditions. One-year-old MM.106 apple (Malus × domestica Borkh.) trees grown under greenhouse conditions in 10 L pots were treated with nutrient solutions. All treatments were applied proportionally based on the volume ratio of material recommended for organic apple orchard field production. A nutrient solution from GC provided the greatest total nitrogen (N) input over the 12-week experimental period, followed in order by the GR, PL, WC, CF, SP, and NF treatments. The PL- and GR-treated plants had the largest stem diameter, largest leaf area, longest stem extension, and fastest dry matter production rate, as well as greater carbon dioxide (CO2) assimilation, SPAD readings, N accumulation, and N use efficiency.

Growth and Soil Chemical Property of Small Apple Trees as Affected by Organic Fertilizers and Mulch Sources

BACKGROUND: This study was conducted to evaluate the effects of the fertilizer sources and ground cover mulches on nutrient release, growth, and photosynthesis in small one-year-old apple (Malus domestica Borkh.) trees in controlled conditions. METHODS AND RESULTS: Treatments included no fertilizer (NF), commercial organic fertilizer (CF), and poultry litter (PL) for fertilizer treatments, and wood chips (WC), shredded paper (SP), green compost (GC), and grass clippings (GR) for cover mulch treatments. All treatments were applied proportionally based on the volume ratio equivalent to the soil. CF, PL, and GR treatments that had optimum carbon (C) and nitrogen (N) ratios (less than 30:1) for N mineralization through the microbes released the greatest concentrations in the pot media at 90 days after the treatments, but GC mulch with the optimum C:N ratio did not. CF-, PL- and GR-treated plants had the largest leaf area, thickest stem diameter, longest shoot extension, and greater dry matter production. CONCLUSION(s): CF and PL showed an suitable organic nutrient source for improving plant growth in an orchard. Interestingly, GR also could be a nutrient source for tree growth, if vegetation competition is controlled by maintaining vegetation height and recycling enough grass clippings to the soil in an orchard.