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The DVO costs farmers in Germany around 500 million euros.
The benefit is doubtful.
In volume 100, issue 1 of the journal "Berichte über Landwirtschaft", published by the BMEL, a remarkable article is printed on this question (see pdf below!).
The authors Prof. Dr. Kage, Dr. Thomas Räbiger and Prof. Dr. Sieling from the Institute of Crop Science and Plant Breeding of the CAU Kiel analyzed the highest quality 424 winter wheat and 132 winter oilseed rape N-increase trials from the last 20 years in Germany.
This paper is, in my opinion, one of the best analyses on the actual impact of the fertilizer regulation in Germany.
The following fertilization behavior for individual plots was evaluated:
(A) Ex post: fertilization at the real occurring annual optimum = approximately N-tester + N-sensor.
(B) Ex ante: Prediction of fertilization level based on real historical mean values of the eco. Optimum = excellent empirical knowledge
(C) DVO: Fertilization according to DVO
(D) DVO -20%: Fertilization according to DVO minus 20%.
An insight into the quality of the analysis presented here is only to be hinted at with the following illustration of the yield optima of three different winter wheat qualities (A/B, C and E wheat).
From these graphs alone, it is obvious why it is important to align fertilization to individual subplots/plots and to the respective annual optimum. A uniform fertilization according to balance approaches cannot be economical. Here are the results of the analysis summarized and commented by myself:
Winter wheat
Fertilization level and yield: Compared to fertilization according to historical experience (B), around 7% nitrogen can be saved by small-scale adaptation to the N optimum that actually occurs (A). And this with a simultaneous increase in yield. The requirements of the DVO, on the other hand, lead to a drop in the fertilization level to 86% of the N optimum and to a drop in yield of around 2 dt/ha. In the red areas, the fertilization level drops to 73% with a simultaneous yield loss of about 5 dt/ha.
The N fertilization adapted to the respective individual optimum generates the highest economic success with 1511 €/ha. This is roughly equivalent to the N-Sensor® system. N fertilization based on the mean values across all trials performs worse by about 38 €/ha. This is roughly equivalent to the best possible fertilization behavior of a farmer without N-Sensor®. The requirements of the DVO lead to an economic loss of 47 and in the red areas to heavy economic losses of 84 €/ha.
Protein levels decrease by 0.5% when fertilizer is applied according to DVO and by about 0.8% in the red areas. We know similar results from Denmark in the past. Whereby in the long term the protein contents here have fallen to well below 10%.
The N balances under winter wheat move in a corridor of + 43 to - 6 kg N/ha. In order to estimate these values correctly, it is necessary to know that N losses (atmospheric, incorporation into humus/microorganisms, leaching) also occur under uncultivated soils and cannot be influenced. The orders of magnitude vary strongly, on average one can assume 30-50 kg N/ha.
Fertilization according to DVO or DVO-20% leads to negative N-balances. In general, negative N balances, i.e. not only winter wheat, but in all crops, over a longer period of time lead to:
- a reduction of humus and soil fertility (contrary to the CO2 and humus discussion, this is like braking and accelerating at the same time) and
- to a decrease of the basic yields (yield without N). Therefore, increasingly higher N fertilization rates are needed later to achieve optimal yield. However, the rigid calculation of N fertilization by the DVO does not allow for this. The result is an accelerating downward movement of yields. The scientific data basis from long-term endurance trials on this is clear, but will not be further elaborated here.
Winter oilseed rape
Fertilization level and yield: As in winter wheat, N fertilization at the real optimum (A) of the plot is the superior strategy. A yield 0.6 dt/ha higher than variant B is realized with 5% less nitrogen. With DVO, N applications decrease to 72 and 58%, respectively, and yields drop 3-5 dt/ha.
The N-balances for winter oilseed rape range from 101 kg N/ha to 35 kg N/ha for the DVO-20% variant. It has long been known that winter oilseed rape has a comparatively poor N balance in a single year. This results from the massive build-up of leaf biomass and the then relatively low N removal by the seeds. However, this is unavoidable. Winter wheat, which usually follows, can take up an average of about 20 kg N/ha in the fall. The high preceding crop value of winter rape for WW ultimately also comes from the higher residual N amounts from the previous year. With a sensibly directed N fertilization of winter wheat in the following year, this nitrogen is used up again and is not problematic.
Effect on N-leaching
Decisive for the assessment of the meaningfulness of the DVO is its influence on the goal of reducing the nitrate concentration in the leachate. At a particularly leaching-prone site (Hohenschulen in SH), the N leaching for the crops WW, WG and WRaps was modeled using a dynamic water model. N balances from -100 to +300 kg N/ha were "generated".
The following statements can be made:
- In pure mineral fertilizer systems there is no correlation between balance surplus (-100 to +200 kg N/ha) and N leaching! The N-output is about +10 to +30 kg N/ha and this is independent of the N-balance!
- Below 100 kg N/ha balance surplus with combined organic-mineral fertilization there is only an insignificantly (max. 15 kg N/ha) higher N shift!
- In a Danish meta-study, renowned scientists come to the conclusion that per kg N/ha balance surplus, approximately 0.3 kg NO³-N leaching is to be expected. So even at 100 kg N/ha balance surplus, which in itself is very very high, we are talking about only 30 kg N/ha nitrate leaching.
- From another study, scientists are quoted who report a "far-reaching insensitivity of nitrogen leaching compared to nitrogen fertilization below the economic optimum".
Conclusion
- With the present study, the ecomic effects and the effectiveness of the restrictions on the intended target can be quantified. When transferring the results from plot trials to a farm manager and to practice plots, a further decrease in the quality of the agronomic plot can be expected. Variants B, C, and D are likely to be worse both economically and in their effects on the N balance than presented here in the study.
- Long-term effects of too low N balances or negative N balances are not included here. However, it is sufficiently known from long-term field studies, which have run over many decades, that a negative spiral of yield development will set in with long-term fertilization below the optimum.
- According to this analysis, the economic damage caused by DVO amounts to 50 to 80 €/ha in winter wheat cultivation and 100 to 155 €/ha in winter oilseed rape. If these figures are roughly extrapolated to the total area of Germany, these two crops alone will cause immediate economic damage of at least €250 million. If the red areas and the other crops are included, this damage will add up to a good 500 million euros. This does not include the long-term effects.
- With proper fertilization in the optimum range, there is no connection between N balance and N leaching. In this respect, any discussion of fertilization at/around the optimum and N-balances below 100 kg N/ha is not expedient.
- Fertilizing according to rigid systems, i.e. N-balancing, is at best intelligent guesswork and never leads to economic success. A pure N-fertilization oriented to the optimum of the individual area by means of the N-sensor is the preferred solution for the achievement of both goals, highest economic efficiency and precaution for drinking water.
Further information can be found in the current test report by Prof. Dr. Hennig Kage, Dr. Thomas Räbiger and Dr. Klaus Sieling of the Institute for Crop Production and Plant Breeding Christian-Albrechts-Universität zu Kiel. Read more here.
Autor: Peer Leithold
Write an email to: peer.leithold@agricon.de
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1 comment(s) for "The DVO costs farmers in Germany around 500 million euros."
Michael Schulz wrote on 10.06.2022, 12:03 - Kommentar Das sind die Erklärungen zum Thema Düngung, die unseren Tier- und Umweltschützern und unseren Agrarpolitikern unbedingt näher gebracht werden sollten ....