Browsing by Person "Flessa, Heinz"

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Effects of liquid manure application techniques on ammonia emission and winter wheat yield
(2023) ten Huf, Martin; Reinsch, Thorsten; Zutz, Mareike; Essich, Christoph; Ruser, Reiner; Buchen-Tschiskale, Caroline; Flessa, Heinz; Olfs, Hans‐Werner
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.
Evaluation of calibrated passive sampling for quantifying ammonia emissions in multi‐plot field trials with slurry application
(2023) ten Huf, Martin; Reinsch, Thorsten; Kluß, Christof; Essich, Christoph; Ruser, Reiner; Buchen‐Tschiskale, Caroline; Pacholski, Andreas; Flessa, Heinz; Olfs, Hans‐Werner
Background: There is a great need for simple and inexpensive methods to quantify ammo- nia emissions in multi-plot field trials. However, methods that meet these criteria have to be thoroughly validated. In the calibrated passive sampling approach, acid traps placed in the center of quadratic plots absorb ammonia, enabling relative comparisons between plots. To quantify ammonia emissions, these acid trap samplings are scaled by means of a transfer coefficient (TC) obtained from simultaneous measurements with the dynamic tube method (DTM). However, dynamic tube measurements are also comparatively costly and time-consuming. Aims: Our objective was to assess the best practice for using calibrated passive sampling in multi-plot field trials. One particular challenge in such experiments is to evaluate the influence of ammonia drift between plots. Methods: In a series of eight multi-plot field trials, acid traps and DTM were used simulta- neously on all plots to measure ammonia emissions caused by different slurry application techniques. Data obtained by both methods were correlated, and the influence of the ubiquitous ammonia background on both methods was evaluated by comparing net values, including the subtraction of the background with gross values (no background subtraction). Finally, we provide recommendations for calculating a TC for calibrating relative differences between plots, based on simultaneous acid trap and dynamic tube measurements on selected plots. Results: Treatment mean values obtained by both methods correlated well. For most field trials, R2 values between 0.6 and 0.8 were obtained. Ammonia background concentrations affected both methods. Drift between plots contributed to the background for the acid traps, whereas the contamination of the chamber system might have caused the back- ground for the DTM. Treatments with low emissions were comparatively more affected by that background.