Fertilization strategy affects crop nutrient concentration and removal in semi-arid U.S. Northwest

Authors: Bierer, Andrew; Dungan, Robert - Rob; Tarkalson, David; Leytem, April

Submitted to: Agronomy Journal
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 9/3/2022
Publication Date: 2/14/2023
Citation: Bierer, A.M., Dungan, R.S., Tarkalson, D.D., Leytem, A.B. 2023. Fertilization strategy affects crop nutrient concentration and removal in semi-arid U.S. Northwest. Agronomy Journal. 115(1):351-369. https://doi.org/10.1002/agj2.21212.
DOI: https://doi.org/10.1002/agj2.21212

Interpretive Summary: The growing dairy industry in southcentral Idaho, USA, is driving an increase in the use of manure and manure products (composts) to meet crop nutrient requirements. Moreover, there is some evidence that these products may impact crop nutrient contents. This has implications pertaining to animal consumption of forages, suitability for human consumption/use, and nutrient management within cropping systems utilizing manure or manure products. Therefore, this study was performed to identify differences in soil nutrient concentration, crop tissue concentration/removal, and forage quality in three regionally important crops (corn, barley, alfalfa) arising from use of manure and manure products to meet crop nutrient requirements. It was found that compost and manure fertilization strategies increased plant tissue concentrations of Nitrogen, Phosphorous, and Potassium while decreasing plant tissue Ca and Mg in some crops. Furthermore, Idaho state specified nutrient removal rates for crops should consider the effect a history of organic amendment has on removal rate. The typical regional application rate of manure (56 Mg ha-1) would rapidly necessitate Phosphorus-based soil nutrient management. Malting barley protein content increases sharply in response to manure application, warranting increased caution in these systems for maintaining malt extract quality. In summary, manure and manure products provide an alternative to synthetic fertilization strategies in the region while maintaining crop yield; specific cases require increased attention to prevent unintended consequences.

Technical Abstract: Access to manure is increasing in semi-arid irrigated cropping systems due to an expanding dairy industry. Improved nutrient management references will help meet crop nutrient requirements while abating consequences of nutrient surplus. A study was conducted from fall 2012 to 2019 utilizing: fall or spring applied dairy manure (56 Mg ha-1), fall applied composted dairy manure (33 Mg ha-1), spring applied urea or SUPERU® and an unfertilized control on a corn-barley-alfalfa3 crop rotation. This manuscript focuses on treatment effects on (i) soil N, P, Olsen-P, K, Ca, Mg, Mn, Na, conductivity, and pH; (ii) crop uptake and removal of N, P, K, Ca, Mg, and Mn; and (iii) forage digestibility and energy content. Compost and manure additions increased corn silage N, P, K respectively by 0.86, 0.28, and 2.4 g kg-1 over other treatments; silage Ca and Mg were depressed 0.4 and 0.53 g kg-1 by manure applications. Mean barley grain Premoval and Kremoval increased 5.10 and 7.65 g kg-1 under manure applications relative to urea and SUPERU treatments while CP (19.1 g N kg-1) neared the limit for high quality malt extract (16-19 g N kg-1). Compost and manure respectively increased alfalfa K by 2.3 and 5.5 g kg-1 over other treatments, approaching levels of concern for hypocalcemia in dairy cattle (=30 g K kg-1). No major impact on corn silage or alfalfa quality parameters, outside of nutrient density, were observed. As nutrient uptake and removal was altered by fertilization strategy, planners may consider revising uptake and removal references.