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  • Author or Editor: Karen Klonsky x
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We address whether it is better for a producer to own harvesting equipment or hire a custom harvester to perform the job. A comparison of calculated purchase costs with the cost of hiring a custom operator leads to an estimate of the break-even acreage, which is used as a decision criterion. However, two risk factors must be included in the decision process: the date of harvest and the efficiency of the harvest operation. The affect of these factors may significantly alter the “real” costs of owning vs. hiring a custom operator and, therefore, change the decision reached by an individual grower.

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A kiwifruit vineyard converted to an organic farm was compared to a conventionally farmed vineyard from 1990 through 1992. February or March applications of composted chicken manure (organic plot) or NH4N O3 plus CaNH4 (NO3)3 through microsprinklers during the growing season (conventional plot) were applied to give equal rates of N. Soil analyses indicated no differences in nutrient or salt levels. Nitrogen leaf levels from the organic plot were consistently lower than those from the conventional system but were not deficient. Leaf concentrations of sodium and chloride increased over the three-year period in the organic plot, but not to phytotoxic levels. Organically grown fruit was as firm or firmer than conventionally grown fruit at harvest and four months after harvest. Damage from latania scale or omnivorous leaf roller was minimal in both plots until 1992, when the organic plot had 3.9% scale compared to 0% in the conventional plot. An economic analysis comparing the short-term profitability of the two systems will be presented.

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Despite the worldwide importance of overhead, mechanized irrigation for crop production, the potential of this technology has been poorly studied in California. Field studies were conducted at Five Points, CA, in 2010 and 2012 to compare the effects of overhead irrigation (OH) and drip irrigation (DR) on transplanted tomato (Solanum lycopersicum) crop growth and yield. Similar amounts of water were applied to both systems in each year to match crop evapotranspiration demands. Crop growth measured by percent canopy coverage and aboveground biomass accumulation were similar between the OH and DR systems early in the growing season in both years but were lower in the OH system during the second half of each season. Tomato yield was 38% greater in 2012 than in 2010 and averaged over the 2 years, 48% higher in the DR than in the OH systems, respectively, due presumably to the higher soil water evaporation losses of the OH system relative to the DR system and also, we propose, to the ability of the drip system to very precisely apply in-season fertigations directly to the crop root zone while OH fertigations were applied at the soil surface and over a greater area. Soluble solids concentration of fruit in 2010 was 5.99% for the DR system and 6.65% for the OH system providing further evidence of water stress in the OH tomatoes. Production costs associated with transitioning from a subsurface drip tomato crop to a sprinkler or surface drip-irrigated crop such as onion (Allium cepa) or garlic (Allium sativum) could be $130 to $420 per acre lower with the OH system compared with the drip system, if yields were maintained. Because operation and labor costs of OH systems are typically lower than those of DR systems, further research on OH irrigation of tomato is warranted to address the shortcomings of OH management that this study has identified.

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Eliminating tillage passes is a means to reduce production costs and dust emissions in California's San Joaquin Valley tomato production region. Inserting winter cover crops between summer crops may be a way to add organic matter to the soil and thereby improve soil quality. From 1999, we evaluated conservation tillage (CT) and cover cropping (CC) in a tomato/cotton rotation in Five Points, Calif. During the course of the study, tillage operations were reduced an average of 50% in the CT system relative to the standard tillage (ST) approach. Yields in the CT no cover crop (NO) system matched or exceeded yields in the STNO system in each year. Tomato yields in the CTCC and STCC systems were comparable to the STNO except in the first year, when stand establishment and early season vigor were problems. Weed management and machine harvest efficiency in high surface residue systems are issues requiring additional work in order to make CT adoption more widespread.

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Legume/cereal mixed winter cover crops are commonly used by organic growers on the central coast of California, but they are unable to provide sufficient nitrogen (N) for a high N-demanding vegetable crop such as broccoli and supplemental fertilizer application may be necessary. The goals of this project were to evaluate the contribution of N from a mixed legume/cereal cover crop (CC) and feather meal and blood meal as organic fertilizers (OF) to an organic broccoli crop and to evaluate economic benefits of CC and OF to the subsequent organic broccoli crop. Trials were conducted at two sites (A and B) with different management histories. Cover crops were grown over the winter and incorporated into the soil in the spring and subsequently broccoli [Brassica oleracea L. (Italica group)] was grown in 2006 at both sites and in 2007 at B only. Cover crop and no CC treatments were grown with supplemental organic fertilizers at four fertility levels (0, 84, 168, and 252 kg N/ha of OF) with four replicates. Generally broccoli head yields at A (14.9 to 26.3 Mg·ha−1) were higher than at B (0.7 to 17.4 Mg·ha−1 in 2006 and 5.5 to 17.9 Mg·ha−1 in 2007). Yield and aboveground biomass N were significantly increased by OF at rates up to 168 kg N/ha at A and to 252 kg N/ha at B and by CC in 2006 at both sites but not in 2007 at B. Although N content of the CC was similarly low at A (2006) and at B (2007), immobilization of soil mineral N occurred only at B. This suggests that the addition of a low N content CC was offset by high N mineralization from the soil at A with a long organic management history (greater than 33 years). Supplemental fertilizer applications may be necessary to achieve optimal yields, but the amount needed can be reduced by cover cropping in fields with a long history of cover crop-based organic management (A) or when cover crop N content is sufficiently high to prevent immobilization (B, 2006). Soil NO3-N patterns suggest a pre-side dress nitrate test may also be useful for N management in organic broccoli. Use of cover crops increased net return above harvest and fertility costs when the yield reduction by N immobilization did not take place. However, the net return increase by the use of cover crops tended to diminish as the rate of OF application increased.

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Traditional processing tomato (Solanum lycopersicum) production in California’s Central Valley relies heavily on tillage to produce high yields. However, recent research and farm innovation have produced a variety of conservation tillage (CT) management alternatives that cut costs, reduce soil disturbance, and produce fewer emissions. A 12-year study in Five Points, CA, demonstrated that CT methods reduced tractor passes by 40%, lowered tillage costs by ≈$80 per acre in 2011 dollars, and achieved comparable yields as standard tillage (ST) methods. As comparable yield performance and net profitability are further demonstrated, an array of CT systems will become increasingly attractive to producers and more common in Central Valley tomato growing areas.

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