this study was to assess the effects of chitosan as a soil amendment on lettuce growth, chlorophyll fluorescence, and gas exchange. Materials and methods Plant materials and experiments . Two trials, each with four replications, were conducted in a
Chenping Xu and Beiquan Mou
Maria Gannett, Marvin P. Pritts, and Johannes Lehmann
biological properties by providing soil amendments varying in C:N ratios and tilling at two different depths, and then determine if these had an impact on soil health indicators, plant establishment, growth, and yield. We hypothesized that adding soil
Rebecca Nelson Brown and Josef H. Gorres
in randomized order within each section. The experimental unit for all data collection was the individual subplot. This pseudoreplication of the main plots facilitated incorporation of the soil amendments; the relatively small area occupied by the
Shawna Loper, Amy L. Shober, Christine Wiese, Geoffrey C. Denny, Craig D. Stanley, and Edward F. Gilman
from a depth of 122 to 213 cm (Hills Dirt Pit, LLC.). Composted dairy manure solids (compost; Agrigy, Palm Harbor, FL) were applied as an organic soil amendment at a rate of 508 m 3 ·ha −1 (5-cm depth, equaling ≈256 Mg·ha −1 ) in combination with two
Nikolaos Ntoulas, Panayiotis A. Nektarios, and Glykeria Gogoula
), which returns some of the nutrients taken up during olive tree cultivation to the croplands ( Tomati et al., 1996 ). Composting and the subsequent use of olive mill byproducts (OMC) as soil amendments in agriculture have significant advantages, including
Horticultural schools are always looking for fresh material for their classes. The Canadian Sphagnum Peat Moss Association (CSPMA) has developed a lesson plan entitled Growing Media and Soil Amendment that is ideal for horticultural or greenhouse management courses. The teaching plan includes terms and definitions on all types of peatmoss and commonly used terms related to the resource. It discusses characteristics and qualities of world peat resources as well as comparisons of physical, chemical, and biological properties of organic materials used in growth media and as soil amendments. In addition to the research information on peat and other soil amendments, the teaching plan addresses the environmental issues surrounding the use of wetlands, including peatlands and the effects of peat harvesting on the environment. The plan introduces students and instructors to the reclamation and restoration efforts that have been developed and used to preserve the harvested bogs in Canada. The curriculum is divided into two sections: one for the students, which includes handouts and one for the instructor, with more in-depth background information.
Jeffrey Norrie, Chantal J. Beauchamp, and André Gosselin
Residues and by-products resulting from papermaking and recycling are receiving increased attention as beneficial soil amendments. Our research examines de-inked and primary paper sludge as a principal constituent of several substrate mixtures used as soil amendments in landscape horticulture. Three factors will be examined in a strip-split-plot design with four replications: substrate mixture (with organic soil and sand), fertilizer level, and plant species. Several paper sludge–organic soil–sand mixtures (maximum 50% sludge) were compared to an organic soil–sand control. A 15-cm layer of each mixture was incorporated into existing soil to a depth of 30 cm. Species of Spiraea, Physpcarpus, and Thuja were grown in addition to Kentucky bluegrass (seed and sod) and ryegrass (seed). Growth, rooting, and plant nutrition (foliar analysis) were examined. Preliminary results indicate poor ground cover and N deficiency in plants grown in all unfertilized plots. For sod and seeded grasses, control plots were slightly more healthy than sludge-amended plots, which was likely due to a greater concentration of available N from the organic soil. The bush species exibited similar responses. We conclude that a base fertilization is needed to decrease the C: N ratio of these substrates to ≈20 to 30 for sustained plant growth regardless of sludge amendments. Toxicity effects were due to the presence of organic contaminants, heavy metals, or both.
Organic farming has increased to a $4.2 billion industry in the U.S. and continues to expand ≈20% annually. In Iowa alone, organic acreage for all crops has increased from 13,000 in 1995 to 120,000 in 1998. Organic farmers have requested an unbiased analysis of natural soil amendments/fertilizers and compost products on the market for certified organic vegetable and herb production. In our first-year trials at the ISU Muscatine Island Research Farm in 1998, a total of 1,120 `Hungarian wax' pepper plants were transplanted into rows at 31 × 61-cm spacing. Four replications of seven fertilization treatments were planted within the field. The goal of the fertilization program was to obtain equivalent nitrogen and calcium rates in the organic and conventional systems. Leaf height was not significantly different in plants fertilized with organic compost (poultry litter-based) at 50 and 100 kg/ha N compared with conventional fertilizers (at 100 kg/ha N). All organic and conventional treatments had greater biomass than the organic and conventional controls (no fertilizer), respectively (ANOVA, P = 0.05). First harvest fresh weights were greater in the organic treatments, with the greatest number of peppers and greatest fresh weight in the compost plus Bio-Cal® (a liming industry by-product) treatment. Total pepper fresh weight over the five harvest periods was not significantly different among treatments, demonstrating to organic farmers that comparable yields can be obtained in systems employing alternatives to synthetic nitrogen fertilizer.
Qingren Wang, Yuncong Li, and Waldemar Klassen
A pot experiment with summer cover crops and soil amendments was conducted in two consecutive years to elucidate the effects of these cover crops and soil amendments on `Clemson Spineless 80' okra (Abelmoschus esculentus) yields and biomass production, and the uptake and distribution of soil nutrients and trace elements. The cover crops were sunn hemp (Crotalaria juncea), cowpea (Vigna unguiculata), velvetbean (Mucuna deeringiana), and sorghum sudangrass (Sorghum bicolor × S. bicolor var. sudanense) with fallow as the control. The organic soil amendments were biosolids (sediment from wastewater plants), N-Viro Soil (a mixture of biosolids and coal ash, coal ash (a combustion by-product from power plants), co-compost (a mixture of 3 biosolids: 7 yard waste), and yard waste compost (mainly from leaves and branches of trees and shrubs, and grass clippings) with a soil-incorporated cover crop as the control. As a subsequent vegetable crop, okra was grown after the cover crops, alone or together with the organic soil amendments, had been incorporated. All of the cover crops, except sorghum sudangrass in 2002-03, significantly improved okra fruit yields and the total biomass production (i.e., fruit yields were enhanced by 53% to 62% in 2002-03 and by 28% to 70% in 2003-04). Soil amendments enhanced okra fruit yields from 38.3 to 81.0 g/pot vs. 27.4 g/pot in the control in 2002-03, and from 59.9 to 124.3 g/pot vs. 52.3 g/pot in the control in 2003-04. Both cover crops and soil amendments can substantially improve nutrient uptake and distribution. Among cover crop treatments, sunn hemp showed promising improvement in concentrations of calcium (Ca), zinc (Zn), copper (Cu), iron (Fe), boron (B), and molybdenum (Mo) in fruit; magnesium (Mg), Zn, Cu, and Mo in shoots; and Mo in roots of okra. Among soil amendments, biosolids had a significant influence on most nutrients by increasing the concentrations of Zn, Cu, Fe, and Mo in the fruit; Mg, Zn, Cu, and Mo in the shoot; and Mg, Zn, and Mo in the root. Concentrations of the trace metal cadmium (Cd) were not increased significantly in either okra fruit, shoot, or root by application of these cover crops or soil amendments, but the lead (Pb) concentration was increased in the fruit by application of a high rate (205 g/pot) of biosolids. These results suggest that cover crops and appropriate amounts of soil amendments can be used to improve soil fertility and okra yield without adverse environmental effects or risk of contamination of the fruit. Further field studies will be required to confirm these findings.
Marilyn B. Odneal and Martin L. Kaps
The recommendation for planting highbush blueberry (Vaccinium corymbosum L.) in Missouri includes the incorporation of sphagnum peat in the planting hole. This experiment compared the use of fresh and aged pine bark to sphagnum peat as soil amendments at planting. One-year-old highbush blueberry `Blueray' plants were planted in 1983 at Mountain Grove, Mo. Plant height, spread, and number of new canes were recorded from 1983 through 1987. Yield and berry size were recorded from 1985 through 1988. There were no significant differences in these measurements among soil amendment treatments (P = 0.05).