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

Abstract

AbstractAccess to livestock manure is increasing in semi‐arid cropping systems of U.S. Northwest prompting evaluation of fertilization strategies on regional production systems. A study conducted from fall 2012 to 2019 used: fall‐ or spring‐applied dairy manure (56 Mg ha−1), fall‐applied composted dairy manure (33 Mg ha−1), spring‐applied urea or SUPERU (Koch Agronomic Services), and a control (n = 6) on a corn (Zea mays L.)–barley (Hordeum vulgare L.)–alfalfa (Medicago sativa L.)–alfalfa–alfalfa rotation. The effects of fertilization strategies on (a) soil nutrients, (b) crop tissue nutrient concentration and removal, and (c) digestibility and energy content of forages are discussed. 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. Barley grain Premoval and Kremoval increased 5.10 and 7.65 g kg−1 under manure applications relative to urea and SUPERU treatments while crude protein (CP) (19.1 g N kg−1) neared limits of high‐quality malt extract (16–19 g N kg−1). Compost and manure 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, were observed. Present Idaho nutrient removal estimates were representative of corn and alfalfa, but not barley in which observed N removal was 28% lower. In 17 of 18 instances, contrast testing suggested nutrient removal differed under organic amended treatments, suggesting nutrient removal modifiers in production systems receiving organic amendment may need established.