Agronomic Values of Anaerobically Digested Cattle Manure and the Separated Solids for Barley Forage Production

Abstract

As biogas production expands, digestates from that industry are increasingly available as potential nutrient sources for crop production, but their agronomic value is poorly understood. Thus, a 5-yr field experiment was conducted to determine the agronomic values of anaerobically digested solid beef cattle feedlot manure (ADM) and the separated solids (SS) from ADM under a semiarid reduced-tillage dryland barley (Hordeum vulgare L.) forage cropping system. Three organic amendments, ADM, SS, and undigested solid beef cattle feedlot manure (CM), were applied annually at 200 or 400 kg total N ha −1 for 4 yr, while the residual effect was examined in the fifth year. The higher N and P availability in ADM translated into greater barley forage yields, total N uptake, amendment-derived N uptake, and apparent N recovery (ANR) from ADM-amended soil than SS-and CM-amended soils, while there were no significant differences between soils receiving SS or CM. The ANR was 22% for ADM but only 12% for CM and 9% for SS. In contrast, P uptake, the fraction of amendment-derived P uptake, and apparent P recovery were similar among all amendments. Similar yields, ANR, post-harvest soil NH 4 , NO 3 , and Olsen-P concentrations between SS-and CM-amended soils suggest that they have a comparable agronomic value. Less residual Olsen-P in soil receiving ADM than SS or CM suggests that ADM is a lower risk for P accumulation when applied at N-based rates. We recommend that current agronomic values for cattle feedlot manure could be applied to SS but not ADM.

Anaerobically Digested Cattle Manure Supplied More Nitrogen with Less Phosphorus Accumulation than Undigested Manure

“…The ANR by barley from separated solids and manure was about four times greater than pellets. The ANR by barley from the digestate, cattle manure, and separated solids was similar to values for digestate (22%), cattle manure (12%), and separated solids (9%) reported by Hao et al (2016) for southern Alberta (about 500 km south of the field site). Although Hao et al (2016) did not study Table 5.…”

“…The ANR by barley from the digestate, cattle manure, and separated solids was similar to values for digestate (22%), cattle manure (12%), and separated solids (9%) reported by Hao et al (2016) for southern Alberta (about 500 km south of the field site). Although Hao et al (2016) did not study Table 5. Barley forage yield, N uptake and P uptake mean values in response to four annual applications of anaerobically digested solid beef cattle manure (digestate), the separated solid fraction from the anaerobically digested cattle manure (separated solids), pelletized dried separated solids (pellets), undigested cattle manure (manure), and a non-amended control (0).…”

Short-term nitrogen dynamics in a soil amended with anaerobic digestate

“…Apparent N recovery values were in the range (32%-45%) reported by Cavalli et al (2016) in a 3 yr field study with a cattle slurry and corn-based digestate applied to Italian ryegrass in northern Italy but higher than the values (19%-22%) reported by Hao et al (2016) and Thomas et al (2017) for a 4 yr field experiment in Alberta, or values in an incubation study (20%-26% for solid digestate cattle manure) by Chiyoka et al (2014). Lower ANR in solid-separated digestate was also reported by Cavalli et al (2016) that can be associated to lower NH 4 + /total N ratio in solid verses liquid fraction of digestate.…”

Recycling Agricultural Wastes and By-products in Organic Farming: Biofertilizer Production, Yield Performance and Carbon Footprint Analysis

“…In particular, according to Møller et al [13] the solid digestate fraction can contain 60-80% of the organic matter and phosphorus, 20-25% of the nitrogen and 10-15% of the potassium compared to the original material. However, since phytotoxicity, viscosity and odor limit the direct application of digestate on agricultural soils, pre-treatments are required to obtain a valuable biofertilizer, thus allowing sustainable crop cultivation without environmental risks [14]. To improve the quality of this pre-processed solid fraction, co-composting could be a feasible way, providing easily degradable materials to foster the microbial activity during the treatment [15].…”