Field studies were conducted at 2 sites to evaluate preplant activated charcoal root dips in reducing herbicide injury to newly planted strawberries (Fragaria × ananassa), In 1981, growth of charcoal treated ‘Prelude’, following application of 0.28 kg/ha terbacil (on 0.5% organic matter, Orangeburg loamy sand), was equal to control plants. Charcoal root dips did not prevent injury from 0.56 and 1.11 kg/ha of terbacil on this soil. In 1982, on Orangeburg loamy sand (0.3% organic matter), injury to ‘Apollo’ by diphenamid (4.5 kg/ha) or napropamide (4.5 kg/ha) applications immediately after planting was reduced by charcoal treatment. On the same soil, alachlor (3.4 kg/ha) or metolachlor (2.2 kg/ha) caused equal amounts of injury with or without charcoal root dips. Some crop protection from terbacil at 0.28 kg/ha was achieved with charcoal; however, none was observed with the 0.42 kg/ha rate.
Poster Session 12—Organic/Sustainable Horticulture 28 July 2006, 12:00–12:45 p.m.
Plants of strawberry (Fragaria × ananassa cv. Tristar) of the same size were grown in 4-inch plastic plots either containing sand or organic soil mix. Plants were watered with solutions of 10, 25, and 50 mM of NaCl, and some with distilled water used as control. Under sunny conditions, the chlorophyll fluorescence measurements indicated that plants growing in sandy soil with 50 and 25 mM of NaCI with Fv/Fm values less than 0.40 tend to show salinity stress after 10 days with 50 mM NaCI, and after 15 days with 25 mM NaCI. Plants grown in organic soil mix do not show stress symptoms at any of the given NaCI concentrations. Plants growing under cloudy days do not show stress symptoms, whether or not the plants were grown in sandy soil or organic soil mix. No significant differences were detected on the total average shoot and root dry weights of plants grown in sandy soils and organic soil mix. However, highly significant differences was detected on the total average shoot dry weight growing under organic soil mix. These data indicate that organic matter reduces the effect of Na+ and Cl– on strawberry plant growth by decreasing the physiological stress during bright, sunny days. Plant tissue analysis shows that plants grown in organic soil mix absorb far less Na+ and Cl– than in sandy soil. Also, it does seem that strawberry plants can tolerate low concentrations of NaCI ions in the soil solution.
High levels of sphagnum peat in the growing medium promoted growth of asparagus (Asparagus officinalis L. cv. Viking 2K) in a greenhouse study. Application of NH4NO3 > 1 g/pot (84 kg·ha-1 equivalent) was detrimental to root growth. High N rates and high organic matter levels decreased fibrous root development. Shoot dry weight was highly correlated with fleshy root number, root dry weight, and shoot vigor.
Three sweet potato (Ipomoea batatas Lam.) cultivars that varied in vine length were compared at 5 N levels. Increasing N levels increased weight and the percentage of No. 1 grade roots of all cultivars. Vine length did not have a linear effect on yield. The long-vine ‘Centennial’ out-yielded the other cultivars, followed by the short-vine ‘L3-243’ and the intermediate-vine length ‘Goldrush’. N applications linearly increased dry matter, carotenoid (fresh and processed), protein content, and reduced fiber content of all cultivars. Cultivars varied significantly for each quality variable studied with the exception of protein content (fresh wt basis), including dry matter, carotenoids, fiber, firmness, and split roots after processing. N applications had no influence on soil P, K, Ca, Mg, or pH. Organic matter content of the soil was increased slightly by increased N applications, probably as a result of excessive vine growth, which was incorporated into the soil after harvest.
Physiological disorders affect both the appearance and nutritional quality of processing tomatoes intended for whole-peel and diced products. The cause of color disorders, such as yellow shoulder disorder (YSD), involves an interaction between plant genotype and the environment. Soil factors that correlate with the incidence of YSD are soil K, K:Mg ratios, organic matter, and phosphorus. Fields with an organic matter above 3.5% have a lower incidence of YSD. Progress in developing an integrated crop management system that growers and processors can use to profitably improve quality and nutritional value while reducing color disorders of tomato has been made. Decision tools for managing color disorders have been developed. Varieties of tomato differ in their susceptibility to color disorders; thus, variety use may offer growers a strategy to manage fields with low potassium, phosphorus, or low organic matter. Soil K application through drip irrigation was effective when applied at full bloom when the plants were most actively growing. Trials conducted in Indiana and Ohio during the 2003 and 2004 growing seasons demonstrated that weekly K application as a batch injection or solid application improved fruit color and reduced internal whitening. The effect of K addition is toward improved hue and L (lower values), but that trend is not always statistically significant and variety-specific responses are observed. Environmental factors for this response are explored. Managing this complex color disorder will entail minimizing risk of incidence, rather than preventative or curative applications.
The ability to predict moisture and organic matter contents as well as soil particle size distribution of a golf course turf media with the use of near infrared reflectance spectroscopy (NIRS) was investigated. This study compared a new quick test, NIRS, with the use of wet chemical analysis for the evaluation of different soil characteristics. Samples were taken from greens and fairways of central Pennsylvania golf courses and from two turfgrass research centers at The Pennsylvania State Univ. Fresh samples were vertically scanned by 1.27-cm increments, from 400 to 2500 nm, with a near infrared monochromator. Moisture and organic matter contents were evaluated in the laboratory. The pipette method was used to determine the particle size distribution. Correlations of 84% and higher were obtained for the sand, silt, and clay values as well as for the moisture and organic matter contents. NIRS analysis of soil characteristics could become a convenient, rapid, and inexpensive alternative to wet chemical analysis for golf course management.
Many vegetable growers rely on methyl bromide or other soil fumigants to manage soil pathogens, nematodes, and weeds. Nonchemical alternatives such as solarization and organic amendments are as yet largely unproven, but do offer promise of more sustainable solutions. The objective of this study was to evaluate the effects of long-term organic amendments and soil solarization on soil chemical and physical properties and on growth and yield of pepper (Capsicum annuum L.) and watermelon (Citrullus lanatus [Thunb.] Manst.). Main plots consisted of a yearly organic amendment or a nonamendment control. Four subplots of soil sanitation treatments consisted of solarization, methyl bromide, Telone, and nonfumigated. Each subplot was divided into two sub-subplots, one with weed control and one without weed control. Plant biomass was higher in plots with organic amendments than in nonamended plots. There were no differences in marketable pepper and watermelon yields between organic amended and nonamended plots during the 1998-99 and 1999-2000 seasons, respectively. However, higher pepper yields were produced from organic amended plots in the 1999-2000 season. Soil pH and Mehlich 1-extractable P, K, Ca, Mg, Zn, Mn, Fe, and Cu were higher in organic amended plots than in nonamended control plots. Soil organic matter concentration was 3-fold higher in amended soil than in nonamended soil. Effects of soil sanitation and weed management varied with crop and season. The methyl bromide and Telone treatments produced higher yields than soil solarization. In general, weed control did not affect plant biomass and yield for any of the crops and seasons. The results suggest that annual organic amendment applications to sandy soils can increase plant growth and produce higher or comparable yields with less inorganic nutrient input than standard fertilization programs.
80 COLLOQUIUM 2 (Abstr. 636–642) Organic Horticulture
In Quebec, commercial sod is produced on >3000 ha. Generally, ≈20 months are required to produce market-ready sod. When conditions are suitable, harvest of marketable sod is possible within a year. However, intensive management may result in soil compaction and a reduction of the organic matter content. Considering the increasing amount of amendment available, sod production fields could be interesting for their disposal. In this study, visual quality and sod root growth was examined following an application of an organic amendment at 50, 100, and 150 t·ha–1, incorporated to depth of 6 or 20 cm. Plots established on a sandy soil receiving organic amendments had higher visual quality ratings. Bulk density was significantly reduced following compost or paper sludge application to a heavy soil. The shearing strength required to tear sod amended with compost was significantly higher in comparison with control and paper sludge treatments.