Optimal Crop Rotation of Idaho Potatoes

Abstract

Idaho’s potato growers face increasing price and production risks as the potato industry undergoes structural change. In response, producers have shortened potato crop rotation to counteract the price risk. A risk-neutral discrete stochastic sequential programming (DSSP) model was developed to analyze the affects of the shortened rotation on expected revenue with incorporated price and production risks. The results support the following conclusions: land constraints due to equipment, labor, and capital efficiency alter optimal rotations; given no land constraints, a whole farm 607.3 ha simulation yields the same results as a per-hectare analysis with Potatoes-Wheat-Wheat-Potatoes being the optimal rotation; and longer rotation cycles generate the highest expected revenue per-hectare. Additional conclusions were that the open market generates higher expected revenue when compared to contracts; producers can counteract some of the loss of expected revenues in the contracted market with lower production risk from longer rotation cycles; Idaho potato producers may not be operating at a risk-neutral level.

Resumen

Los productores de papa de Idaho enfrentan el aumento de los riegos del precio y de producción a medida que la industria de papa sufre cambios estructurales. En respuesta, los productores han acortado la rotación del cultivo de papa para contrarrestar el riesgo del precio. Un modelo de programación secuencial estocástica discreta (DSSP) de riesgo neutral que incorpora los riesgos de precio y producción fue desarrollado para analizar los efectos de una rotación corta sobre los ingresos esperados. Los resultados justifican las siguientes conclusiones: las limitaciones debidas al equipo, trabajo y eficiencia del capital alteran las rotaciones óptimas; cuando no hay tales limitaciones, el rendimiento total de una granja simulada de 607.3 hectáreas da los mismos resultados que el análisis por hectárea siendo la rotación óptima Papa-Trigo-Trigo-Papa; y los ciclos de rotación más largos generan los ingresos esperados por hectárea más altos. Las conclusiones adicionales fueron que el mercado libre genera los ingresos esperados más altos en comparación con los contratos; los productores pueden contrarrestar algunas pérdidas de sus ingresos esperados en el mercado pactado al tener un menor riesgo de producción cuando se usa ciclos rotación más largos; los productores de papa de Idaho pueden no estar operando a nivel de riesgo neutral.

Appendices

Appendix A—Production Costs

2003 Southeastern Idaho South District Russet Burbank Commercial Potatoes: No Storage

South District: Bannock, Bingham and Power Counties

Budget A/ Publication ID: EBB4-P01–03

University of Idaho

Table 8 Budget/publication ID, EBB4-P01–03 (Patterson et al. 2003a)

Wheat Enterprise Budget

South Eastern Idaho Soft White Spring

Budget/Publication ID: EBB4-SWS-03

University of Idaho

The costs and returns estimate shown here is typical for irrigated soft white spring wheat in southeastern Idaho. Production practices are based on surveys conducted in Bingham, Bonneville, Madison and Power counties.

Table 9 Budget/Publication ID, EBB4-SWS-03 (Patterson et al. 2003b)

Appendix B—Input Variations

Input Variations from Russet Burbank Budget/Publication ID: EBB4-P01–03

Adjustments Occur due to Crop Rotation Cycle and Previous Year’s Disease State

University of Idaho Extension

Herbicide Adjustments:

Prowl is added to existing tank mix for rotations shorter than 3 years; no additional application cost is required.

Insecticide Adjustments:

One Fulfill application is added to rotations shorter than 3 years.

For two continuous years of potatoes (P-P), a second application of Monitor is made.

For three continuous years of potatoes, an in-furrow application of Admire replaces Thimet application.

No additional applications costs are included for insecticide application; assuming that these added insecticides applied with an existing fungicide.

Fungicide Adjustments:

One additional application of Dithane and application cost included in 2-year rotation (W-P) with low to medium previous disease incident.

Three additional fungicides (Dithane, Moncut, and Omega) are added to 1-year rotation (P-P) with low-medium previous disease incident.

A 1-year rotation (P-P) with a high incident of previous disease or for all three and 4-year continuous potatoes (P-P-P) and (P-P-P-P) an additional four applications (Dithane, Moncut, Omega, and Quadris) are added.

Quadris applied 0.4 to 0.6 per 304.8 m of row equaling 0.585 l application per hectare.

Fumigation Adjustments:

The additional application rate of metam sodium changes by rotation, ranging from 374 to 654 l per hectare.

Table 10 Potato crop chemical pricing list

Table 11 Potato chemical applications based on rotation cycle

Appendix C—Potato Yield Adjustments

Adjustments Based on Crop Rotation Cycle and Previous Year’s Disease Occurrence

Yield decreases by 4.483 metric tons per hectare for each year less than 3 years out of potatoes (Miller et al. 2003). The rotation crop is assumed to be wheat.

Table 12 Yield reduction based on rotation cycles (metric tons per hectare)

Table 13 Yields reduction based on previous disease incidence

Appendix D—Soil Borne Disease Probabilities

Dependent upon Crop rotation Cycles and Disease State of the Previous Year

University of Idaho Extension

Table 14 Probability of potato disease occurrence