Soil amendments in transition to organic vegetable production with comparison to conventional methods: Yields and economics

Authors: Russo, Vincent; TAYLOR, MERRITT - OSU, LANE, OK

Submitted to: HortScience
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 8/8/2006
Publication Date: 12/1/2006
Citation: Russo, V.M., Taylor, M.J. 2006. Soil amendments in transition to organic vegetable production with comparison to conventional methods: Yields and economics. HortScience. 41(7):1576-1583.

Interpretive Summary: In order to obtain a US government organic certification producers must conform to specific rules and regulations. Under some conditions it is necessary that the land go through a transition period of at least three years duration before the certification can be conferred. During transitions changes occur in soil that can affect plant development and yield. Materials can be added to the soil that also affect plant development and yield. Included in these materials are humates, a component of soils high in organic material, and corn gluten meal (CGM), an organically certified herbicide and fertilizer. The management of bell pepper (Capsicum annuum L.), cv. Jupiter, cucumber (Cucumis sativus L.) cv. Earli Pik, and sweet corn (Zea mays L.), cv. Incredible (se endosperm genotype), under the transition to organic management was compared using levels of humates (0, 112, 224 kg/ha) and CGM (0, 448, 896 kg/ha) to management using conventional methods. Yields were determined over a three year period and an economic assessment of the management methods was undertaken. Year had an effect on yield. Bell pepper yield in the transition to organic production was lower than in the conventional production system in the first year, but in the final two years yields were equal between management systems. Cucumber yield in the transition to organic production was lower in the first two years than in the conventional production system in the first year, but in the final year yields were equal between management systems. In all years sweet corn yields for plants under conventional production was higher than for the plants in the transition plots. Humate and CGM level did not provide a benefit to yield. Net yields for conventionally produced crops was always higher over the three years. The difference in profit was due to the higher costs involved for crops under transition to organic. It appears that costs of organic production need to be reduced. However, if a premium is assigned to the value of organically grown crops then the costs of production could be mitigated.

Technical Abstract: Most producers who wish to convert to organic production will have to pass through a three-year transition period before their land can be qualified for organic certification. This transition can produce unique challenges for producers. Use of several amendments have received interest for use in organic production. How these affect vegetable production during the transition period was examined, and comparison was made to conventional methods. Land was taken from perennial pasture and converted to production of the vegetables: bell pepper (Capsicum annuum L.), cv. Jupiter; pickling cucumber (Cucumis sativus L.), cv. Earli Pik; and sweet corn (Zea mays L.), cv. Incredible (se endosperm genotype), using organic materials and methods with comparison made to production using conventional methods. Conventional and transition to organic portions of the field were separated by 70 m, with the buffer zone planted with the same sweet corn cultivar as used in the experimental plots and minimally maintained by addition of organic fertilizer. To the organic portion of the field three levels of humates (0, 112, 224 kg'ha**-1), and three levels of corn gluten meal (0, 448, 896 kg'ha**-1) were applied. Yields for all crops were determined for all years. In the first year bell pepper yields for plants under conventional production were higher than for the plants in the transition plots. In the remaining two years bell pepper yields were similar under the two production systems. In the first two years cucumber yields for plants under conventional production were higher than for the plants in the transition plots. In the last year cucumber yields were similar under the two production systems. In all years sweet corn yields for plants under conventional production was higher than for the plants in the transition plots. Humates and corn gluten meal did not benefit yields of any crop. In addition, an economic analysis comparing yields, prices, and costs of production of the crops under conventional and the transition to organic crops indicated that, conventional practices generally provided more net revenue than organic production. Three years of data comparing yields, prices and costs of production of bell peppers, pickling cucumber and sweet corn, using conventional and transition to organic production methods indicated that conventional practices generally provided more net revenue than did transition to organic production methods. Net revenue per hectare, in a single year, ranged from -$6,523 for bell peppers under the transition to organic to $15,131 for conventional bell peppers in 2002 for a difference of $21,654. When net revenue for all crops was combined over three years there was a positive net revenue for those under transition to organic and conventional production. Net revenue for the three crops under the transition to organic for the three years was $3,212 for three hectares. Net revenue for the three crops under conventional production for three years was $64,478 for three hectares. While both organic and conventional production of the three crops produced positive net revenue, the revenue for conventional production was $61,266 greater for three hectares than that of organic production for the three years combined. Costs, yield, and prices will have to be considered when decisions are made concerning the adoption of organic practices.