Effects of Liquid Manure Application Techniques on Ammonia Emission and Winter Wheat Yield

Abstract

Ammonia emissions following liquid manure application impair human health and threaten natural ecosystems. In growing arable crops, where immediate soil incorporation of the applied liquid manure is not possible, best-available application techniques are required in order to decrease ammonia losses. We determined ammonia emission, crop yield and nitrogen uptake of winter wheat in eight experimental sites across Germany. Each individual experiment consisted of an unfertilized control (N0), broadcast calcium ammonium nitrate (CAN) application as well as four different techniques to apply cattle slurry (CS) and biogas digestate (BD). Fertilizer was applied to growing winter wheat at a total rate of 170 kg N ha−1 split into two equal dressings. The following application techniques were tested for both liquid manure types: (i) trailing hose (TH) application using untreated and (ii) acidified (~pH 6) liquid manure (+A), as well as (iii) a combination of open slot injection (SI) for the first dressing and trailing shoe (TS) application for the second dressing without and (iv) with the addition of a nitrification inhibitor (NI) for the first dressing. The highest ammonia emissions (on average 30 kg N ha−1) occurred following TH application of BD. TH application of CS led to significantly lower emissions (on average 19 kg N ha−1). Overall, acidification reduced ammonia emissions by 64% compared to TH application without acidification for both types of liquid manures. On average, the combination of SI and TS application resulted in 23% lower NH3 emissions in comparison to TH application (25% for the first application by SI and 20% for the second application by TS). Supplementing an NI did not affect ammonia emissions. However, decreasing ammonia emissions by acidification or SI did not increase winter wheat yield and nitrogen uptake. All organically fertilized treatments led to similar crop yield (approx. 7 t ha−1 grain dry matter yield) and above-ground biomass nitrogen uptake (approx. 150 kg ha−1). Yield (8 t ha−1) and nitrogen uptake (approx. 190 kg ha−1) were significantly higher for the CAN treatment; while for the control, yield (approx. 4.5 t ha−1) and above-ground biomass nitrogen uptake (approx. 90 kg ha−1) were significantly lower. Overall, our results show that reducing NH3 emissions following liquid manure application to growing crops is possible by using different mitigation techniques. For our field trial series, acidification was the technique with the greatest NH3 mitigation potential.

Replacing Chemical Fertilizer with Separated Biogas Slurry to Reduce Soil Nitrogen Loss and Increase Crop Yield—A Two-Year Field Study

“…This study revealed that water inputs, such as irrigation and rainfall, were the critical factors influencing NH 3 emissions and nitrogen leaching under identical conditions. Water inputs accelerate the downward leaching of nitrogen in the biogas slurry, thereby reducing NH 3 emissions and increasing nitrogen leaching [21][22][23][24]. Rainfall volumes were observed to be 775 mm and 402 mm in the first and second years (Figure 1), respectively, indicating that rainfall was likely the predominant factor driving the aforementioned trends.…”

Evaluation of the Dynamic Tube Method for Measuring Ammonia Emissions after Liquid Manure Application

“…These acid traps are placed in each plot of a field experiment to collect NH 3 to assess relative differences between plots, while the wind speed corrected DTM is used on a few selected plots to scale those relative differences [12]. This approach was used in a wide range of experiments in Germany [4,[23][24][25][26][27] and Denmark [28].…”

‘Soil and Plant Nutrition’—A Section of Agronomy: Advances and Perspectives

“…Nitrogen can be lost from the soil through processes such as leaching, denitrification, and volatilization, which lead to acidification in terrestrial systems, eutrophication of aquatic systems, and decline in biodiversity and contribute to climate change. The most commonly proposed solutions involve optimizing fertilizer doses, as well as considering the form of fertilizers used, such as slow-release fertilizers [6][7][8][9][10][11][12][13][14]. A very promising solution is the application of nitrification inhibitors [15][16][17][18][19][20].…”