Search Results

You are looking at 1 - 10 of 675 items for :

  • decomposition x
Clear All

and into the surrounding soil. These containers readily decompose after being directly installed in the landscape ( Evans et al., 2010 ). In contrast, compostable biocontainers do not decompose quickly enough to allow roots to physically break through

Free access

to promote decomposition. Composted bark is rarely used in Oregon container nurseries due to the additional costs associated with its preparation. Physical and chemical properties of DFB as they pertain to use in nursery container substrates have only

Full access

on the root ball and planted into the field, landscape bed, or final container. They are designed to allow roots to grow through the container walls and to decompose after being planted into the field or final container. Compostable biocontainers are

Full access

fitness in the native peat bog habitat of cranberries, where organic matter decomposition and N mineralization is usually quite limited ( Malmer et al., 2003 ; Svensson, 1995 ). Despite the extensive literature on cranberry-ERM associations based on

Free access

., 2015 ; Kroonenberg, 2008 ; Mørup, 2011 ). In addition, through multiway decomposition, each mode is individually reduced into components allowing easier interpretation of individual data mode trends. Higher-order decompositions are extensions of

Open Access

Long-day onion (Allium cepa L.) `Vision' was submitted to four soil water potential (SWP) treatments using subsurface drip irrigation in 1997 and 1998. Onions were grown on two double rows spaced 22 inches (56 cm) apart on 44-inch (112-cm) beds with a drip tape buried 5 inches (13 cm) deep in the bed center. SWP was maintained at four levels by automated, high frequency irrigations based on SWP measurements at an 8-inch (20-cm) depth. The check treatment had SWP maintained at -20 cbar (kPa) during the entire season. The other three treatments had SWP maintained at -20 cbar until 15 July, then reduced to -30, -50, or -70 cbar. Reducing the SWP level after 15 July below -20 cbar failed to reduce onion bulb decomposition in storage, but reduced colossal onion yield in 1997, and marketable and total yield in 1998.

Full access

Abstract

The possibility of using 31P-nuclear magnetic resonance (NMR) spectroscopy to detect ethephon (ET) in olive leaves has been examined. 31P-NMR spectroscopy can be used as a nondestructive technique (tissues excised but not extracted) with the unique attributes of monitoring ET hydrolysis internally and without radiochemicals. A characteristic spectral peak for the parent ET molecule was found 17-21 ppm (a measure of relative frequency, not concentration) downfield from the H3PO4 reference, and a nonreactive, minor contaminant spectral peak was found at 26-27 ppm. Absolute spectral peak location (“chemical shift”) is pH-dependent. The ET hydrolysis product, orthophosphate, produces a spectral peak at 2 to 3 ppm, which coincides with the broad spectral peak attributed to major endogenous phosphate compounds in leaves, such as inorganic phosphate. The lower limit of 31P-NMR detection of ET in solution was 10−3 m; however, spray applications of ET were not detectable in olive leaves unless concentrations of 5 × 10−2 m or more were used, which is far greater than current agricultural use levels for mechanical harvest of olive. Nevertheless, 31P-NMR spectroscopy was useful in following ET uptake and decomposition for more than 48 hr in olive leaves from xylem-fed shoots, and the resolution of the ET spectral peak into separate, adjoining peaks presents the potential to identify and quantify subcellular compartmentalization of ET according to pH-induced chemical shifts. Such knowledge would contribute to understanding long- and short-term in vivo decomposition of ET to ethylene. Chemical name used: (2-chloroethyl)phosphonic acid (ethephon).

Open Access

mineralization rates for meals adequately supplied N for plant growth ( Snyder et al., 2009 ). Gale et al. (2006) examined decomposition and availability of N released from manure, compost, and specialty products (pelleted organic fertilizer, feather meal, and

Free access

Plant growth and residue decomposition values are needed by the Soil Conservation Service for developing data bases for selected fruit and vegetable crops. These data bases will be used for predicting soil loss using improved erosion prediction technology. The plant growth parameters under investigation are canopy cover leaf area index, plant height plant weight, root weight, stem diameter and vegetative dry matter. The climatic parameter are daily base temperature rainfall and growing degree days. The following is a list of the residue decomposition parameter: 1. Residue weight and harvest 2. Initial carbon-nitrogen ratio, and 3. Percent residue cover at harvest. The results are being used in the WEPP model to predict soil erosion. Data collection afor these parameters start 15 days after planting for vegetables and continue at 7 day intervals through maturity.

Free access

Abstract

Decomposition and metabolism of the ethylene-releasing plant growth regulator, (2-chloroethyl)methylbis(phenylmethoxy)silane (CGA-15281), was studied over a 14-month period in 3 peach orchard soils. The molecule decomposed rapidly when exposed to a soil environment. Major decomposition products were: ethylene, benzyl alcohol, and low levels of (2-chloroethyl)methyl(phenylmethoxy)chlorosilane and (dichloromethyl)(chloroethylmethylphenylmethoxy)disiloxane which appear to be formed in side reactions of CGA-15281 breakdown. The compounds have molecular ions of 247 and 341 and display molecular ion isotope patterns consistent with molecules containing 2 and 3 chlorine atoms, respectively. Methoxy positions on the parent molecule were largely metabolized to CO2, while the ethyl group was primarily liberated as ethylene. The methyl group on the parent molecule remained bound to the silicon atom, forming insoluble organosilicates; little was metabolized by soil microorganisms to CO2. Soil type had a small but statistically significant effect on degree of release of ethylene from the chloroethyl positions; however, it did not affect metabolism of the methoxy group or degree of partitioning of the methyl group into insoluble compounds. This difference in ethylene release could not be explained by differences in pH, percentage of organic matter, or cation exchange capacity of the soils tested. Soil pH had a pronounced effect on the rate of breakdown of the parent molecule with the most rapid decomposition at low pH.

Open Access