meet the nutritional requirements of trees and improve soil fertility while reducing nutrient losses to leaching. The specific objectives of were to 1) examine the effects of combining legume cover crops with low rates of N fertilization on fraser fir
Yingqian Lin, Alexa R. Wilson and Pascal Nzokou
C. Stevens, V. A. Khan, A. Y. Tang and R. M. Cody
Field plots on Norfolk sandy loam soil at Tuskegee and Eufaula, AL were treated by soil solarization (SS). Samples rhizsosphere (R) and nonrhizosphere soil from cole crop and strawberry plots were collected and assayed with selective media for population densities of microbes involved in organic decomposition and mineralization. Microflora population densities of bacteria, actinomycetes and fungi increased 2-7 folds in the solarized compared to the bare soil (BS). Microflora population densities in the soils involved in cellulose and protein decomposition, ammonification, nitrification, phosphate mineralization were greater in solarized soil compared to BS. Nitrogen-fixing bacteria in R soil 7 months after SS was higher when compared to BS at Tuskegee, but was reduced 50 folds 18 months after SS.
Monica Ozores-Hampton, Philip A. Stansly, Robert McSorley and Thomas A. Obreza
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.
I.A. Merwin and W. C. Stiles
Eight groundcover management systems (GMS) have been evaluated since 1986 in an apple orchard replant site. Tree-row GMS have included post-emergence herbicide (glyphosate) “killed sods,” pre-emergence herbicide (norflurazon + diuron) strips, a crownvetch “living mulch,” hay-straw mulch, monthly cultivation, a close-mowed sod, and an unmowed, chemically growth-regulated (maleic hydrazide + 2,4-D) sodgrass. Soil organ&matter content, surface aggregate structure, and water infiltration have improved under vegetative groundcovers relative to herbicide treatments. Extractable soil N, K, P and B have increased under straw mulch. Except for K, foliar nutrient content (dry wt basis) has not been closely coupled with soil nutrient content. Leaf K, P and B contents have increased, while leaf N, Mg and Zn, have decreased in trees in sodgrass relative to herbicide GMS.
Warren Roberts and Bob Cartwright
Raised beds (0.9 m wide, 1.8 m centers, 6.1 m long) were formed in Oct. 1988. Beds were either left bare or seeded with rye (Secale cereale) or hairy vetch (Vicia villosa). Plots were sprayed with glyphosate in April, 1989. Rye was completely killed, but hairy vetch was not. Bed height was maintained best with beds covered with rye. In a 3 by 4 factorial, four rates of nitrogen (45, 90, 134, and 179 kg/ha) were applied to each soil cover treatment. On April 17, cabbage (Brassica oleracea cv. Solid Blue 760) was transplanted two rows per bed, with 30 cm spacing in rows and between rows. There was no mowing or cultivating prior to transplanting. A linear increase in yield was observed with increasing applications of nitrogen. The cabbage yield was less in rye than in vetch orbare soil. The yield difference between rye and bare soil was more pronounced at the low rates of nitrogen than at the high rates of nitrogen. Cabbage grown in rye had significantly fewer aphids, thrips, and cabbage loopers than did cabbage grown in bare soil.
James H. Cane and Daniel Schiffhauer
Cranberry flowers (Vaccinium macrocarpon Ait.) require bee visitation for pollination. Bees visit cranberry flowers for nectar and sometimes pollen, but honey bees (Apis mellifera L.) in particular often work alternative co-flowering species for nectar, presumably because cranberry offers inferior nectar rewards. In a common garden setting, replicated plots of the cultivar Stevens were found to secrete significantly more nectar sugar (25% to 35% more) per flower than either `Ben Lear' or `Early Black', two other common commercial cultivars. The nectar secretion rate of `Stevens' was unaffected by a 4-fold range of fertilizer application rates over the preceding 2 years. These results are compared to studies of other crops involving varietal differences and programs of selective breeding for nectar secretion.
B.K. Hamilton and L.M. Pike
A field study was conducted on TG1015Y onions (Allium cepa L.) grown in the Lower Rio Grande Valley of Texas. Treatments included two soil types (clay & loam), four harvest dates throughout the bulbing process, and two S rates [0 kg S/ha (standard) & 22.4 kg S/ha (high)]. Laboratory analysis included pyruvic acid concentration for pungency measurement, percent dry matter, and sucrose, glucose, and fructose concentrations. Harvest date influenced all variables tested. Percent dry matter generally decreased as bulbs matured (8.0 to 6.9% DM) with a slight increase at maturity (7.4% DM). Enzymatically developed pyruvic acid concentrations ranged from 3.13 to 4.03 μmole/g fresh wt. There was an upward trend of pyruvic acid over the bulbing process. Total sugars, measured by HPLC methods, tended to increase during bulb development (39.3 to 46.5 mg/g fresh wt.). However, sucrose decreased during the last two harvests causing a corresponding increase in glucose and fructose. The S treatment had no effect on any of the factors measured. The only influence by soil type was sugar concentration, with the loam field being higher in glucose.
Adam Montri and J.A. Biernbaum
management issues include site preparation, soil health, soil moisture, and soil fertility. Our focus is on methods suitable for organic certification. Site preparation If the soil is not already in production, key objectives for site preparation include
Matt A. Rudisill, Bruce P. Bordelon, Ronald F. Turco and Lori A. Hoagland
maintain or improve soil quality within these systems. Organic fertility amendments have potential to improve soil quality while meeting nutrient needs in high tunnel systems. However, timing nutrient availability with periods of critical nutrient uptake
Jennifer Moore-Kucera, Anita Nina Azarenko, Lisa Brutcher, Annie Chozinski, David D. Myrold and Russell Ingham
via optimal fertility management is a common goal among conventional and organic growers. In addition, improving soil health is a requirement for organic growers [§205.203a ( National Organic Program, 2002 )]. Soil health has been defined as the