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- Author or Editor: Nancy E. Roe x
Utilization of municipal waste composts on vegetable crops may be advantageous if research can determine appropriate product maturity and quality standards, application methods and rates, application timing, and supplemental nutrient requirements. Experiments using compost for seed germination and seedling growth indicate that mixtures of compost with amendments such as perlite and vermiculite result in acceptable growth rates, but often require additional N and K for optimum growth. In the field, compost generally improves soil characteristics for vegetable crop growth. Tests using compost rates from 12 to 336 t·ha–1 either increased or did not change yields of vegetable crops. Highest yields are often produced from a combination of composts with additional nutrient sources. When the composts were used as mulches, vegetable crop growth and production were generally higher than from plants in unmulched plots, but lower than those from plots with polyethylene mulches. If growers are to accept the use of composts, the compost must be a consistent product, and yield increases must be high enough to justify the costs of transporting and applying the compost.
In many areas, dairies and other concentrated animal operations must modify their waste handling systems. Utilization of locally produced manures by vegetable production operations may increase crop yields while preventing discharge of potentially polluting nutrients into waterways. Composting is often recommended to stabilize nutrients, lower the volume of manure, and produce a product that may control some plant diseases. However, composting has costs in time and equipment, so some growers prefer using uncomposted manure. Dairy manure compost at 22 (LC), 45 (MC), or 90 (HC) t·ha–1 or dairy lot scrapings at 45 t·ha–1 (FM) were tilled into soil before seeding a dryland cantaloupe (Cucumis melo L.) crop. All plots, including an unamended control (UC), were fertilized with a total of 23N–14P–0K (kg·ha–1). After removal of the cantaloupe in late summer, drip irrigation was added, broccoli (Brassica oleracea var. botrytis Mill.) seedlings were transplanted into the identical plots, and 112N (kg·ha–1) was sidedressed. Cantaloupe yields from FM, LC, MC, HC, and UC plots were 5.4, 3.4, 2.1, 4.5, and 1.5 t·ha–1, respectively. Broccoli yields from FM, LC, MC, HC, and UC plots were 4.1, 3.6, 4.4, 4.1, and 2.2 t·ha–1, respectively. All rates of compost or manure increased yields of cantaloupe, and the subsequent broccoli crop. Use of the manure resulted in highest increase in potential net income from sales of cantaloupe and broccoli.
Rapid production of compost often results in crop damage by phytotoxic compounds or high C/N ratios in immature (uncured) compost. The influence of immature biosolids-yard trimmings compost on germination and growth of cucumber (Cucumis sativus L.) was evaluated. Germination percentages of cucumbers seeded in equal parts (v/v) of compost and vermiculite were similar to those in vermiculite. When screened compost was placed in flats and compared with flats of potting mix or sandy field soil, germination percentages were 98, 96, and 89 for mix, sand, and compost respectively. Germination in compost-amended field plots was higher than in soil when cucumbers were planted 1, 2 or 10 weeks after compost application, but similar in 3 and 5 week plantings. Use of this immature compost increased, decreased, or did not affect cucumber seed germination, depending on media and growing conditions.
The Atlantic hurricane season stretches from June to November, and the vegetable growing season in South Florida begins in August. This means that pre-plant, planting, and early harvesting operations are performed during hurricane season. Three major hurricanes striking our area during two consecutive growing seasons have helped to teach us how to give vegetable crops the best chance of survival. On a 4-ha farm growing diversified vegetable crops, there have been clear differences in crop survival. Tiny seedlings of most crops were generally killed by driving rains and strong winds. However, 7- to 10-cm-tall transplants in plastic cell trays survived surprisingly well when placed on the ground in an area that did not flood and was protected from flying debris. During the hurricane with the highest winds, large plants, such as tomatoes and squash, were defoliated. Even plants that survived defoliation and regrew were injured, so they were vulnerable to diseases later in the season. It actually appears to be best not to stake crops in extremely high winds. Staked and tied tomatoes often broke off at the top string. In winds of over 90 knots, unstaked eggplants fared best of any mature crops. They fell over immediately and, lying on the ground, were protected from the high winds. After the storm passed, they were pulled upright, staked and tied, and produced excellent yields. Sweet corn also fell over, but, over a period of a week, gradually returned to about a 45° angle where it produced about 30% of the normal yield. Of course, each hurricane has different characteristics; what works in one may not be the best during others. We are, however, hoping not to have a chance to learn more about how crops survive hurricanes.
Composts may improve crop growth in sandy soils. A biosolids-yard trimming compost (C) was incorporated into sandy soil at 134 t·ha–1 (49.7% moisture) before applying polyethylene mulch. Fertilizer (F) was applied at 0%, 50%, and 100% of the grower's rate (71N–39P–44K t·ha–1 broadcast and 283N–278K t·ha–1 banded in bed centers). `Elisa' pepper transplants were planted 20 Jan. 1994. Marketable fruit weights were 20, 31, and 32 t·ha–1 without C and 30, 35, and 32 t·ha–1 with C for 0%, 50%, and 100% F, respectively. Pepper fruit weights increased with increasing F rates and were higher in plots with C than without C. Without removing mulch, `Thunder' cucumbers were seeded on 26 Sept. 1994. Marketable fruit weights were similar at the three F levels, but were 23 and 27 t·ha–1 without and with C, respectively. One application of C significantly increased bell pepper yields and a subsequent cucumber crop.
A mulch of municipal solid waste compost at 224 t·ha was compared with glyphosate sprays and a nontreated check for weed control in vegetable crop bed alleys during Spring and Summer 1992. In both experiments, there was a significantly lower percentage of weed coverage in the compost mulch and herbicide spray plots than in the control plots. Weed control in the compost and herbicide treatments was similar. In the spring experiment, tractor tire traffic through the alleys reduced weed growth in all plots by 62 % and 44% at 16 and 73 days after treatment initiation, respectively. These results suggest that municipal solid waste compost may have potential as a viable mulch for weed control in vegetable crop alleys. Chemical name used: isopropylamine salt of N -(phosphonomethyl) glycine (glyphosate).
The composition of composts derived from municipal solid wastes can affect emergence and seedling growth. Composts consisting of biosolids and yard trimmings [standard compost (SC)] alone or with mixed waste paper (MWP), refuse-derived fuel (RDF), or refuse-derived fuel residuals (RDFR) were evaluated in seedling trays and pots for vegetable crop seedling emergence and growth. In trays, tomato (Lycopersicon esculentum Mill.), cucumber (Cucumis sativus L.), and pepper (Capsicum annuum L.) seedlings emerged faster from a commercial peat-lite mix and from sandy field soil than from the composts. Plants were tallest and shoots were generally heaviest in the peat-lite mix and aged SC and smallest in the field soil. MWP compost generally inhibited early seedling growth more than RDF or RDFR composts. Among the composts, seedlings were tallest and heaviest in SC. In pots, growth of each vegetable was generally greatest in SC, followed by other composts, and lowest in sandy soil. Tomato and pepper seedling emergence was more sensitive to the inhibitory effects of the RDF, RDFR, and MWP composts than cucumber seedling emergence. Fertilizer increased plant growth in each medium except SC, in which cucumber stem diameter was not increased. Adding MWP, RDF, or RDFR to SC generally decreased seedling emergence and growth. The composts prolonged days to emergence and decreased percent emerged seedlings. However, subsequent seedling growth in composts was equal to or greater than seedlings in the peat-lite mix and much greater than those in the sandy field soil.
Compost (biosolids and yard trimmings at 134 t·ha-1) was applied to a sandy field soil with fertilizer at 0%, 50%, or 100% of the grower's standard rate (71N-39P-44K kg·ha-1 broadcast and 283N-278K kg·ha-1 banded in bed centers). Raised beds were constructed and covered with polyethylene mulch, and `Elisa' bell peppers (Capsicum annuum L.) were transplanted into the plots. Foliage samples taken at early harvest indicated that leaf N concentrations increased and Cu concentrations decreased with increasing fertilizer rates. Leaf concentrations of P, K, Ca, and Mg increased and Cu decreased in plots amended with compost. Marketable pepper yields from plants grown in plots amended with compost were 30.3, 35.7, and 31.1 t·ha-1 in plots with 0%, 50%, and 100% fertilizer rate, respectively. Without compost, yields were 19.8, 31.1, and 32.0 t·ha-1 with 0%, 50%, and 100% fertilizer rate. `Valient' cucumbers (Cucumis sativus L.) were seeded through the same polyethylene mulch into the previous pepper plots. Marketable cucumber yields were not affected by residual fertilizer, but were higher (26.8 t·ha-1) in plots amended with compost than without compost (22.7 t·ha-1). In a second experiment, a biosolids-yard trimming-mixed waste paper (MWP) compost and a biosolids-yard trimming-refuse-derived fuel (RDF) compost were applied at 0 or 134 t·ha-1 with fertilizer at 0%, 50%, or 100% fertilizer rates, respectively. With no fertilizer, total yields from pepper plants were higher in plots amended with composts than without composts. In 50% fertilizer plots, yields were similar between compost treatments. At 100% fertilizer rate, yields with MWP compost were significantly higher than yields with RDF compost or with no compost. In plots without fertilizer or with 50% fertilizer rates, mean fruit size (g/fruit) was largest with MWP compost, intermediate with RDF compost, and smallest without compost. With 100% fertilizer, mean fruit size was larger with either compost than without compost. Composts combined with low rates of fertilizer generally produced higher pepper yields than other treatments. Residual compost increased yields of a subsequent cucumber crop. Yields from pepper plants without fertilizer were higher when soil was amended with composts with added MWP or RDF, but, with fertilizer, yields were similar or only slightly increased.