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  • Author or Editor: Johnnie R. Schmidt x
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Some possible alternatives to soil fumigation with methyl bromide include soil solarization and the use of composts to modify soil microorganism populations. We tested combinations of solarization and compost on a broccoli (Brassica oleracea var. botrytis L.) crop on an organic farm. Treatments were: solarization with compost (SC); solarization without compost (SW); compost only (NC); and an untreated control (NW). Dairy manure compost was applied manually to compost plots at 22 Mg/ha, raised beds were constructed, and solarization plots were covered with clear polyethylene from 13 July to 26 Aug. Black polyethylene mulch was applied to all plots, covering the clear polyethylene. Broccoli, cv. Packman, transplants were planted into the beds and fertilized with fish emulsion fertilizer three times for a total of ≈22 kg/ha N. Broccoli heads were harvested on 1, 5, and 9 Dec., trimmed to 15 cm, weighed and counted. Marketable yields were 8704, 7117, 8169, and 8374 (kg/ha) and mean head weights were 353, 228, 286, 313 (g) for SC, SW, NC, and NW, respectively. Under these conditions, head weights were highest with compost and solarization, and marketable yields were similar.

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Affluent “peri-urban” populations in some areas have created new markets for small specialized growers. Although intensive growing systems using drip irrigation and fertigation with new varieties can increase yields, there is also a desire to use systems that are viewed as more sustainable. One way to reduce the environmental impact of intensive systems is to use organic mulches that do not require disposal and can improve soil conditions. `Chandler' strawberry (Fragaria ×ananassa Duch.) transplants were set in raised beds on 28 Oct. 1997. All plots received pre-plant P at 73 kg/ha. Treatments were: hay mulch (HY); a commercial, pelleted, recycled paper mulch (PA); polyethylene mulch (PL); or a woven weed-blocking (WB) fabric, with or without dairy manure compost (22% moisture) at 22 t/ha tilled in before bedding. A total of 184 kg/ha N was applied through the irrigation system in weekly applications during the growing season. The first bloom set was killed by cold on 9 Mar. 1998. Yields from the two synthetic mulch systems (PL = 5502 and WB = 4996 kg/ha) were significantly higher than those from the organic mulches (HY = 2824 and PA = 1735 kg/ha). Mean fruit weight was also higher with synthetic (PL = 10.6 and WB = 10.4g) than organic (HY = 9.5 and PA = 9.0 g) mulches. Factors such as increased weed growth in organic mulches and warmer temperatures in synthetic mulches contributed to increased yields from synthetically mulched plots.

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