A fertile soil should be capable of supplying all the elements plants need for growth. Fertility is an essential component of soil health and productivity. Not only must nutrients be present in the soil, they need to be in a form the plant can use. Since these ionized forms of nutrients are soluble in water, plant roots can absorb them along with the water they take up. The rate at which nutrients become available is affected by weather, irrigation, soil type, pH, and fertilizer applications. Nutrients present in forms other than ions are not directly available to plants although they do represent reserves that can become available in the future.
Five different pools of soil nutrients can be found in soil. The “rocks and minerals” pool is also called parent material. This parent material can be a rich source of nutrients, but they release very slowly, generally over decades to hundreds of years depending on climate and rainfall. Organic matter is also a pool of nutrients that slow-release over just a few seasons. When cover crops, manure, compost, or organic fertilizers are added to the soil their nutrients are not immediately available to plants. The organic matter must first be broken down by microorganisms. As the organisms feed and die, nutrients release gradually into the ion form plants can take up.
Two other pools that concentrate nutrients are the surfaces of clay and humus particles. Because of their extremely small size, humus and clay particles have large amounts of surface area relative to their volume. Their surfaces have negative charges which make them very attractive to positive charged cations, which means clay-rich soils have a larger cation exchange capacity (CEC) than sandy soils. However, those with sandy soils can greatly increase their cation exchange capacity through the addition of organic matter and the creation of humus.
The fifth pool represents the nutrient pool immediately available for plant uptake: those nutrients currently in the soil solution, the mixture of water and nutrients in the soil. This pool is in equilibrium with the clay and humus nutrient pools. As nutrients are taken by plants from the soil solution, they are replaced by the nutrients adsorbed to the clay and humus particles. Increasing soil organic matter can increase cation exchange capacity, especially in sandier soils. Research continues on adequate crop nutrition in organic and sustainable systems.
Nutrient Recovery: Products from dairy manure to improve soil fertility
Benedict, C., J. Harrison, S. Hall, G. Yorgey. 2018. Washington State University. FS305E.
Yorgey, G., W. Pan, R. Awale, S. Machado, A. Bary. 2017. Chapter 7 In Yorgey, G. and C. Kruger, eds. Advances in Dryland Production Systems in the Pacific Northwest. Washington State University Extension, Pullman, WA.
Soil Fertility Management
Borrelli, K., T. Maaz, W. Pan, P. Carter, H. Tao. 2017. Chapter 6 In Yorgey, G. and C. Kruger, eds. Advances in Dryland Production Systems in the Pacific Northwest. Washington State University Extension, Pullman, WA.
Phosphorus Uptake by Potato from Fertilizers Recovered from Anaerobic Digestion
Collins, H. P., E. Kimura, C. S. Frear, and C. E. Kruger. 2016. Agron. J. 108:2036-2049. doi:10.2134/agronj2015.0302
The Rationale for Recovery of Phosphorus and Nitrogen from Dairy Manure
Yorgey, G., C. Frear, C. Kruger, T. Zimmerman. 2014. WSU Extension Fact Sheet FS136E. This fact sheet is part of the AD Systems Series.
Precision Nitrogen Application: Eric Odberg Case Study
Yorgey, G., S. Kantor, K. Painter, H. Davis, and L. Bernacchi. 2014. Video and text farmer case study. Eric Odberg is a fourth generation farmer who practices no-till management and was an early adopter of variable rate nitrogen (VRN) application in the dryland production region of the Pacific Northwest.
Nitrogen Management and Climate Change Mitigation in Pacific Northwest Cropping Systems
Nitrous Oxide Emissions in Inland Pacific Northwest Cropping Systems
Nitrogen Cycling and Losses in Agricultural Systems
Soil Fertility in Organic Systems: A Guide for Gardeners and Small Acreage Farmers
Collins,D. C. Miles, C. Cogger, R. Koenig. 2013. Pacific Northwest Extension Publication PNW646.
Soil Testing: A Guide for Farms with Diverse Vegetable Crops
Collins, D. 2012. Washington State University Extension. EM050E.
Northwest Soil Science: Nitrogen Mineralization
Soil Scientist Doug Collins published an article on Readthedirt.org that explains his research on how and when soil nutrients are available to crops.
A Fine Thin Skin – wind, water, valcanoes and ice
Steury, 2011. Article highlighting CSANR soil research in Washington State Magazine.
Potential nitrogen contributions from legumes in Pacific Northwest apple orchards
Mullinix, K. and Granatstein, D. 2011. Intl. J. Fruit Sci. 11:74-87.
Composts and Nutrient Management
The WSU Puyallup Research Center faculty have conducted extensive work on compost, manure and biosolids. This website provides information on yard waste and food waste composts, clopyralid, calculating bulk density, nutrient management for organic systems and compost facility operator training events. The site has links to the Compost Mix Calculator the Organic Fertilizer Calculator and Center research publications.
Closing the recycling loop through organic amendments in agriculture and gardens
Recorded webinar (online presentation) from Jan 2011 by Craig Cogger, Crop and Soils Scientist and Extension Educator. This seminar discusses research and guidelines on soil amendment choices based on use, nitrogen availability, carbon sequestration potential, handling nutrient imbalances in organic amendments, and an update on herbicide issues in some composts.
Building Markets for Biofertilizers — Perceptions and Performance
Video of keynote address by Chad Kruger at the 26th Annual BioCycle West Coast Conference April 2012.
Struvite as a Phosphorus Fertilizer Source for Greenhouse Crop Production – webinar
This webinar highlights recent research by Rita Hummel of WSU on struvite as a phosphorus source for greenhouse production of bedding plants and vegetable starts. Her research includes struvite derived from municipal wastewater and dairy manure. Craig Cogger opened the webinar with a brief overview of the phosphorus challenge. After Rita’s presentation of greenhouse research results, Keith Bowers discussed struvite production as one phosphorus removal technology for wastewater at livestock, food processing, and public sewage treatment sites. The webinar closed with a brief summary by Craig and an open question period.
Helping Sustain Agriculture in Africa
WSU scientist Lynne Carpenter-Boggs is working with an international group of scientists to help find bean varieties and microbial inoculates that will improve yields on the ancient soils that farms in many parts of Africa must contend with. Dr. Carpenter-Boggs took a Flip camera to Africa and shot some wonderful footage of farms, people and animals.
Extracting valuable energy, carbon and nutrient resources from organic waste
WSU scientists have conducted extensive research on Anaerobic Digestion (AD) as a technology for recovery of methane (energy), stable carbon, and nutrients from organic wastes such as manure, food processing wastes and the organic fraction of municipal solid wastes (OFMSW). Our research has evaluated the technical and economic performance of commercially available systems, developed improved AD reactors, and commercialized WSU patented nutrient recovery technology. This webinar, presented by CSANR director Chad Kruger and CSANR scientist Craig Frear, will provide an update on the latest results from the WSU Climate Friendly Farming Project’s AD research.
Organic Farming Systems and Nutrient Management
Beginning in 2002, organic amendments, cover crops, and soil quality have been investigated in our farming systems experiment. An interdisciplinary team is studying a range of issues important to smale scale, direct-market, and organic agriculture, including nutrient management, soil quality, weed management, economics, marketing, and on-farm research.
Organic Fertigation Products – April 2010
Article in Sustaining the Pacific Northwest Newsletter
Influence of orchard floor management and compost application timing on N partitioning in organically managed apple trees
TerAvest, D., J.L. Smith, L. Carpenter-Boggs, L. Hoagland, D. Granatstein, and J.P. Reganold. 2010. HortScience. 45:637-642.
Influence of biodynamic preparations on compost development and resultant compost extracts on wheat seedling growth
Reeve, J.R., L. Carpenter-Boggs, J.P. Reganold, A.L. York, and W.F. Brinton. 2010. Bioresource Technology.
Land Application – A true path to zero waste?
Organic Waste to Resources Research and Pilot Project Report. Brown, S., K. Kurtz, C. Cogger and A. Bary, March 2010. Ecology Publication Number 09-07-059. This study tested the benefits of compost and biosolids applications to soils. Benefits included increased C and N levels, improved soil bulk density, water holding capacity and crop yield.
Site-Specific N Management for Direct-Seed Cropping Systems
Greenhouse Gas Fluxes from Irrigated Sweet Corn (Zea mays L.) and Potato (Solanum tuberosum L.)
Life Cycle Assessment of the Potential Carbon Credit from No- and Reduced- Tillage Winter Wheat in the U.S. Northwest
Monitoring Carbon Sequestration and Greenhouse Gas Emissions from Irrigated AgroEcosystems
CropSyst Simulation of the Effect of Tillage and Rotation on the Potential for Carbon Sequestration and on Nitrous Oxide Emissions in Eastern Washington
Comparative Analysis of Nitrous Oxide Fluxes in Dryland Cropping Systems
Yield, Protein and Nitrogen Use Efficiency of Spring Wheat: Evaluating Field-Scale Performance
Organic Waste to Resources Research and Pilot Project Report: Producing Energy and Fertilizer from Organic Municipal Solid Waste: Enhancing Hydrolysis and Bacterial Populations and Mixing and Thermodynamic Modeling of New Solid Waste Treatment Technology
Usama Zaher, Shulin Chen, Chenlin Li, Liang Yu, and Timothy Ewing, June 2009. This project developed, tested and modeled a high solids anaerobic digester consisting of a solids reactor and a leached liquids UASB for reacting volatile fatty acids. At near neutral pH the system improves methane production 50% over existing digesters, while return flow reseeds the solids digester with high titer micro-organisms that improved biological kinetics. The dual reactors system provides for control of digester limiting acid and ammonia processes, while allowing for nutrient recovery, and significantly improves performance for capital outlay.
Proceedings of the Department of Ecology’s Beyond Waste Workshop (2009)
A special workshop planned by CSANR and hosted by the Department of Ecology Waste 2 Resources Division to feature state-funded research projects relating to the topics of recovering energy and resources (including soil amendments) from organic wastes.
Orchard floor management effects on nitrogen fertility and soil biological activity in newly established organic apple orchard.
L. Hoagland, L. Carpenter-Boggs, D. Granatstein, M. Mazzola, J. Smith, F. Peryea, and J. Reganold. 2008. Biology and Fertility of Soils online.
Monitoring Greenhouse Gas Fluxes from an Irrigated AgroEcosystem – Fall 2008
Article in Sustaining the Pacific Northwest Newsletter