Response of soil health indicators to long‐term dairy manure in a semiarid irrigated cropping system

Abstract

Dairy manure fertilization is an important practice to return nutrients to agricultural soils, but there is limited knowledge regarding the effect of manure on soil health metrics in semiarid irrigated row crops. The objective of this research was to determine how long-term dairy manure application affects biological and chemical indicators of soil health in a field experiment in southern Idaho. The treatments were no fertilizer, inorganic fertilizer (IF), and dairy manure applied annually or biennially at rates of 17, 35, and 52 Mg ha -1 on a dry weight basis. Spring soil samples were collected 7 yr after project initiation at depths of 0-15 cm and 15-30 cm and analyzed with soil health metrics that are commonly used to quantify organic matter pools and biological nutrient cycling via enzyme activities and N transformation rates. Soil organic C increased with increasing application rate and more than doubled after 7 yr of annual manure at the highest application rate. In general, C and N pools, enzyme activities, and N transformation rates were greater at 0-15 cm than deeper in the soil profile. Compared with IF, annual and biennial manure treatments had a significant effect on most indicators at both soil depths, which increased with increasing manure application rate. Because of the strong response of the indicators to dairy manure, all were found to be positively and significantly correlated with each other, suggesting that only a small subset of the metrics tested could potentially be used to evaluate the influence of manure on soil health in the region.

Cropping systems with perennial vegetation and livestock integration promote soil health

“…MinC tends to be more sensitive to manure use relative to POXC or SOM (Hurisso et al., 2016). Applying manure had no effect on POXC in some studies (Jokela et al., 2009; Wienhold, 2005), but others found greater POXC associated with manure use (Dungan et al., 2022; Min et al., 2003; Mirsky et al., 2008). On farms in North Carolina, both soil organic C and soil test biological activity were 50%–55% greater in fields receiving organic amendments (Franzluebbers, 2020a).…”

“…MinC tends to be more sensitive to manure use relative to POXC or SOM (Hurisso et al, 2016). Applying manure had no effect on POXC in some studies (Jokela et al, 2009;Wienhold, 2005), but others found greater POXC associated with manure use (Dungan et al, 2022;Min et al, 2003;Mirsky et al, 2008).…”

Predicting nitrogen mineralization from dairy manure and broadleaf residue in a semiarid cropping system

“…In the present study, as manure application rates increased, there was a concurrent increase in soil N and P potentially enhancing microbial processes. In 2019, Dungan et al (2022) evaluated a variety of soil health indicators in soils from the present study. They reported that potentially mineralizable N, microbial biomass N, and potential ammonia oxidation rates, as well as a variety of other biological indicators, increased with increasing manure application rates with both annual and biennial applications.…”

“…These changes can affect N immobilization and mineralization. Long‐term additions of manure also increase microbial abundances and enhance soil enzyme activities that impact cycling of C and N in soils (Ashraf et al., 2020; Dungan et al., 2022; Masunga et al., 2016; Wang et al., 2022). Many studies have evaluated the effects of a one‐time application of manure; however, long‐term application of manure may enhance the residual N pool that is available for mineralization in subsequent years, and therefore short‐term studies may underestimate future plant‐available N from manure (Mallory et al., 2010).…”

Soil health indicators reveal that past dairy manure applications create a legacy effect

“…Few studies have been conducted to assess the effects of cattle manure (beef or dairy) on soil health indicators (chemical and biological) in irrigated semiarid cropping systems (Dungan et al, 2022;Elzobair et al, 2016;Lupwayi et al, 2019;Miner et al, 2020). In southern Idaho, Dungan et al (2022) found that enzyme activities and N transformation rates were significantly greater in soils amended with high rates of dairy manure for several years. In the semiarid environment of Lethbridge, Canada, Lupwayi et al (2019) reported that increased enzyme activities could be detected decades after the last beef cattle manure application, with significantly greater microbial biomass and enzyme activity under irrigated versus rainfed conditions.…”