Benefits and tradeoffs of reduced tillage and manure application methods in a Zea mays silage system

Abstract

A critical question is whether there are agricultural management practices that can attain the multiple management goals of increasing yields, preventing nutrient losses, and suppressing greenhouse gas (GHG) emissions. No-till and manure application methods, such as manure injection, can enhance nutrient retention, but both may also enhance emissions of nitrous oxide (N 2 O), a powerful GHG. We assessed differences in soil N 2 O and carbon dioxide (CO 2) emissions, nitrate and ammonium retention, and crop yield and protein content under combinations of vertical-till, no-till, manure injection, and manure broadcast without incorporation in a corn (Zea mays L.) silage system. During the growing seasons of 2015-2017, GHG emissions and soil mineral nitrogen (N) were measured every other week or more frequently after management events. Crop yield and protein content were measured annually at harvest. No-till reduced CO 2 emissions but had no impact on N 2 O emissions relative to vertical-till. Manure injection increased N 2 O and CO 2 emissions, with the magnitude of this effect being greatest for 1 mo post-application. Manure injection also increased soil ammonium and nitrate but did not increase yield or crop quality relative to broadcast application. Similarly, tillage did not affect crop yield or protein content. Despite the tradeoffs between mineral N retention and elevated GHG emissions, manure injection in no-till systems benefits farmers by reducing soil carbon losses as CO 2 , retaining mineral N, and maintaining crop yields and quality.

Measuring the Supply of Ecosystem Services from Alternative Soil and Nutrient Management Practices: A Transdisciplinary, Field-Scale Approach

“…Importantly, our study suggests that appropriately sized grassed waterways at the edge of field can be so effective in reducing nutrient rich surface runoff, that they dominate the impact of soil and nutrient management strategies like CCMIRT. The tradeoff in climate regulation services aligns with other research in our bioregion finding that manure injection increases N 2 O emissions by subjecting manure to anaerobic conditions in the soil, as opposed to surface application [20,49]. Our study reinforces the importance of better understanding soil greenhouse gas emissions and their drivers, as well as the importance of including them in ecosystem service assessments.…”

“…Greenhouse gas fluxes (carbon dioxide, CO 2 , and nitrous oxide, N 2 O) were measured using a portable model 1412i infrared photoacoustic spectroscopy (PAS) gas analyzer (Model 1412i, Innova Air Tech Instruments; calibrated as in Iqbal et al [47] using static chamber protocols [48] and established sampling techniques [47,49]. Five chambers were placed randomly in each field.…”

“…This variability is particularly high during acute management activities such as injecting manure. While the use of individual static chambers used for greenhouse gas emissions measurements may not capture the full range of emissions, our sampling methods are standard methods designed to try to account for spatio-temporal variability [47,49]. To address spatial variability, we placed five chambers randomly across each field to capture a range of field variability, and were careful to place chambers relative to acute management activities such that chambers covered the range of field conditions (e.g., placing chambers such that they incorporated soil affected by injection strips and soil not affected by injection strips).…”

Management zone‐based estimation of positive and negative nitrous oxide flux in organic corn fields

“…) was consistent with other studies finding more frequent late-season N 2 O consumption in systems using inorganic(Adviento-Borbe et al, 2007;Kumar et al, 2014;Lehman et al, 2017) and organic amendments(Davis et al, 2019;Dittmer et al, 2020). The net N 2 O flux measured on Day 1 after the rain was significantly greater than typically observed on Day 2 (P < .05, Figure2d) but did not decline further on Days 3 and 4.…”

Nitrous oxide emissions are driven by environmental conditions rather than nitrogen application methods in a perennial hayfield

“…Nitrogen (N) is essential for maintaining soil fertility and crop productivity in agricultural systems, but there are multiple pathways by which applied N can leave a field before crop uptake, resulting in negative agronomic and environmental Manure injection is often promoted for reducing N and phosphorus runoff as well as decreasing NH 3 emissions (Cantarella et al, 2018;Chadwick et al, 2011;Clemens et al, 1997;Dell et al, 2012), but a potential tradeoff is that it can also increase emissions of N 2 O, a greenhouse gas with a warming potential 273 times that of CO 2 over 100 years (Forster et al, 2021), compared to surface application of manure (Dittmer et al, 2020;Duncan et al, 2017;Rodhe et al, 2006). Manure injection creates conditions that are simultaneously favorable for N retention as NH 3 and N loss as N 2 O by placing manure slurry in slots that extend 2.5-5 cm into the soil profile.…”