Potato Nutrient Management in Sustainable Cropping Systems

American Journal of Potato Research, Jul/Aug 2005 by Stark, J C, Porter, G A

ABSTRACT

Sustainable nutrient management involves a set of management practices designed to conserve soil resources, to maintain or enhance productivity, and to help reduce growers' reliance on chemical fertilizers. Sustainable nutrient management systems wall most certainly rely heavily on the use of legume rotation crops and/or organic soil amendments. To realize the full benefit to the crop ecosystem, Sustainable nutrient management programs will also likely require longer crop rotations with less frequent potato production. There is considerable research evidence indicating that these systems can maintain or increase productivity while having positive impacts on nutrient supply, soil physical properties, and soil conservation. However, their successful adoption and continued use on a large scale will require resolution of uncertainties related to economic risk associated with inconsistent nutrient availability in alternative nutrient management systems, potential environmental risks associated with excessive P applications in animal manures, and the potential for increased potato pest incidence resulting from manure application.

RESUMEN

El manejo sostenible de nutrientes incluye un conjunto de practicas dise�adas para conservar los recursos del suelo, mantener o intensificar la productividad y ayudar a los agricultores a reducir la dependencia que tienen en los fertilizantes qu�micos. Los sistemas de manejo sostenible de nutrientes conf�a mayormente en el uso de leguminosas como cultivos de rotaci�n y/o enmiendas org�nicas del suelo. Para darse cuenta del beneficio del ecosistema del cultivo, el programa de manejo sostenible de nutrientes requerir� de per�odes m�s largos de rotaci�n y de cultivos de papa menos frecuentes. Existe una considerable evidencia de investigaci�n que indica que estes sistemas pueden mantener o incrementar la productividad y al mismo tiempo tienen un impacto positive sobre el suministro de nutrientes, propiedades f�sicas del suelo y su conservaci�n. Sin embargo, su completa adopci�n y uso continuado en gran escala requerir� de resolver ciertas dudas relacionadas con el riesgo econ�mico asociado a la disponibilidad irregular de nutrientes en los sistemas de manejo alternative, riesgos potenciales del medio ambiente asociados con una excesiva aplicaci�n de f�sforo contenido en el esti�rcol y el potencial para implementar la incidencia de enfermedades como resultado de la aplicaci�n de esti�rcol.

ADDITIONAL KEY WORDS: legumes, crop rotation, cover crops, soil amendments, manure, composted organic material

INTRODUCTION

Nutrient management in most major U.S. potato production areas is highly intensive, relying heavily on chemical fertilizers (Westermann 1993; Westra and Boyle 1991). Extensive chemical use, along with the trend toward shorter potato rotations, has resulted in reduced emphasis on the use of crop rotation and residue management as components of nutrient management programs. In many areas, this has resulted in an overall reduction in organic residue additions to potato-cropping systems that can reduce soil carbon and nitrogen (N) concentrations and increase crop fertilizer N requirements (Zielke and Christenson 1986). By comparison, cropping systems in which large amounts of organic residues from green manures, animal wastes, or composts are applied to the soil have the potential for improved soil nutrient availability, tilth, water-holding capacity, and aeration (Bullock 1992; Honeycutt et al. 1995; Macrae and Mehuys 1985; Smith et al. 1987). Extensive use of crop residues and animal wastes can be a primary factor contributing to the sustainability of a crop production system due to the increased used of renewable on-farm resources and improvements in soil quality.

One of the key limitations to the more extensive use of crop residues and animal wastes as nutrient sources in potato cropping systems has been the relative lack of quantitative information on the effects of different organic residue management practices on nutrient cycling, nutrient-use efficiency and net economic return. Currently, information is fairly limited on the interactive effects of potato-cropping-system components on nutrient dynamics in potato ecosystems (Alford et al. 1996). The fact that N release from organic sources is so closely linked to complex microbial C and N cycles in different crop ecosystems makes quantitative prediction of N availability more difficult than from chemical fertilizer N (Groffman et al. 1987). However, a number of research studies have produced information that can be used to guide the development of nutrient management programs in sustainable potato-cropping systems.

USE OF LEGUMES AS N SOURCES FOR POTATOES

Legumes have received considerable attention as an important component of sustainable cropping systems because they can supply biologically fixed N to subsequent crops. The potential benefits of growing legumes prior to potatoes include (1) contributions of biologically fixed N to the cropping system, (2) improved yield and quality, (3) improved soil physical properties, (4) suppression of soil-borne potato diseases, and (5) N contributions to subsequent crops (Griffin and Hesterman 1991).