Correction: Mauerer et al. Replacing Mineral Fertilizer with Nitrified Human Urine in Hydroponic Lettuce (Lactuca sativa L.) Production. Sustainability 2023, 15, 10684

Mareike Mauerer; Thorsten Rocksch; Dennis Dannehl; Ingo Schuch; Inga Mewis; Nadja Förster; Christian Ulrichs; Uwe Schmidt

doi:10.3390/su17010060

,

and

¹

Division Biosystems Engineering, Albrecht Daniel Thaer-Institute of Agricultural and Horticultural Sciences, Humboldt-Universität zu Berlin, Albrecht-Thaer-Weg 3, 14195 Berlin, Germany

²

Division Urban Plant Ecophysiology, Albrecht Daniel Thaer-Institute of Agricultural and Horticultural Sciences, Humboldt-Universität zu Berlin, Lentzeallee 55/57, 14195 Berlin, Germany

^*

Author to whom correspondence should be addressed.

Sustainability2025, 17(1), 60;https://doi.org/10.3390/su17010060

Version Notes

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The authors would like to make the following corrections to the published paper [1]. The changes are as follows:

Replacing the following sentence in the Abstract:

The calculated carbon footprint from the total fertilizer production was reduced by 34.25%, caused by the nitrified urine treatment.

With the following:

The calculated carbon footprint from the total fertilizer production was reduced by 20.52%, caused by the nitrified urine treatment.

2.: Replacing the first paragraph of Section 2.4:

Fertilizer savings were calculated for each fertilizer salt, comparing the mean amounts used in both treatments given in Table 2. This was done for each nutrient contained in the N, P, and K fertilizers and for each fertilizer salt. Assuming a production of 830,000 heads per hectare [36] in [37], savings were expressed as kg ha⁻¹. From these results, the saving potential of CO₂ equivalent [kg CO₂-eq ha⁻¹] was calculated according to the results of Brentrup et al. [38] for CaNO₃ (0.64 kg CO₂-eq kg CaNO₃) and KAS (0.95 kg CO₂-eq kg KAS), and Umweltbundesamt [39] for KH₂PO₄ (1.26 kg CO₂-eq kg KH₂PO₄) and KNO₃ (1.2 kg CO₂-eq kg KNO₃).

With the following:

Amounts of all N, P, K fertilizers were transformed to kilograms per hectare [kg ha⁻¹] assuming a production of 830,000 heads per hectare [36] in [37]. The carbon footprint (CF) of fertilizer production in CO₂ equivalent [kg CO₂-eq ha⁻¹] was then calculated according to the results of Brentrup et al. [38] for CaNO₃ (0.64 kg CO₂-eq kg CaNO₃⁻¹) and KAS (0.95 kg CO₂-eq kg KAS⁻¹), and Umweltbundesamt [39] for KH₂PO₄ (1.26 kg CO₂-eq kg KH₂PO₄⁻¹) and KNO₃ (1.2 kg CO₂-eq kg KNO₃⁻¹).

3.: Adding this sentence at the end of the second paragraph of Section 2.4:

The sum of carbon footprints for both treatments was calculated and expressed in kg CO₂-eq ha⁻¹ and a saving in percent was calculated for the Aurin + mf treatment.

4.: Replacing the first paragraph of Section 3.2:

The calculated CFs for the difference in amounts of mineral fertilizers used in the two treatments are shown in Table 4. The CF for the Aurin + mf treatment was 8003.1 kg CO₂-eq ha⁻¹ compared to 12,763.85 kg CO₂-eq ha⁻¹ for the control treatment, with a resulting difference of 4371 kg CO₂-eq ha⁻¹ or 34.25%.

With the following:

The calculated CFs for the amounts of mineral fertilizers used in the two treatments are shown in Table 4. The CF for the Aurin + mf treatment was 16,933.13 kg CO₂-eq ha⁻¹ compared to 21,305.05 kg CO₂-eq ha⁻¹ for the control treatment, with a resulting difference of 4371.91 kg CO₂-eq ha⁻¹ or 20.52%.

5.: Replacing Table 4:

Table 4. Calculated carbon footprints (CFs) for fertilizer salts of the two experimental treatments.

	Unit	Control	Aurin + mf
Mineral fertilizer extra ¹	-	KAS, KH₂PO_4, KNO₃	CaNO₃
Mineral fertilizer difference ²	[kg ha⁻¹]	3133.72, 171.78, 889.27	607.63
CF mineral fertilizers	[CO₂-eq ha⁻¹]	4260.60	388.88
N from Aurin^® fertilizer	[kg ha⁻¹]	-	869.90
CF urine fertilizer	[CO₂-eq ha⁻¹]	-	8003.1
CF wastewater treatment	[CO₂-eq ha⁻¹]	8503.24	-
CF Total	[CO₂-eq ha⁻¹]	12,763.85	8391.94

¹ Amounts used of fertilizers indicated have positive differences to the other treatment, ² Differences shown are in comparison to the second treatment.

With the following table:

Table 4. Calculated carbon footprints (CFs) for fertilizer salts of the two experimental treatments.

	Unit	Control	Aurin + mf
Mineral fertilizers used	-	CaNO₃, KAS, KH₂PO₄, KNO₃	CaNO₃, KH₂PO₄, KNO₃
Mineral fertilizer amounts	[kg ha⁻¹]	2115.49, 3133.72, 2152.88, 4798.52	2723.11, 1981.11, 3909.24
CF mineral fertilizers	[CO₂-eq ha⁻¹]	12,801.80	8930.08
N from Aurin^® fertilizer	[kg ha⁻¹]	-	869.90
CF urine fertilizer	[CO₂-eq ha⁻¹]	-	8003.1
CF wastewater treatment	[CO₂-eq ha⁻¹]	8503.24	-
CF Total	[CO₂-eq ha⁻¹]	21,305.05	16,933.13

6.: Replacing the first sentence of the second paragraph of Section 4.2:

With the calculated CFs for both treatments, a total saving of 34.25% (12,763.85 CO₂-eq ha⁻¹ vs. 8391.94 CO₂-eq ha⁻¹) of greenhouse gas emissions was possible due to the Aurin + mf treatment.

With the following:

With the calculated CFs for both treatments, a total saving of 20.52 % (21,305.05 kg CO₂-eq ha⁻¹ vs. 16,933.13 kg CO₂-eq ha⁻¹) of greenhouse gas emissions was possible due to the Aurin + mf treatment.

7.: Replacing the first sentence of Section 5:

The proposed fertigation strategy for lettuce (Lactuca sativa var. capitata) with the nitrified urine fertilizer Aurin resulted in the reduced consumption of mineral fertilizers relative to the control (48% of N, 15% of K, and 13% of P) with comparable nutrient use efficiencies between treatments, and thus in a saving of greenhouse gas emissions (34.25%).

With the following:

The proposed fertigation strategy for lettuce (Lactuca sativa var. capitata) with the nitrified urine fertilizer Aurin resulted in the reduced consumption of mineral fertilizers relative to the control (48% of N, 15% of K, and 13% of P) with comparable nutrient use efficiencies between treatments, and thus in a saving of greenhouse gas emissions (20.52%).

The authors state that the scientific conclusions are unaffected. This correction was approved by the Academic Editor. The original publication has also been updated.

Reference

Mauerer, M.; Rocksch, T.; Dannehl, D.; Schuch, I.; Mewis, I.; Förster, N.; Ulrichs, C.; Schmidt, U. Replacing Mineral Fertilizer with Nitrified Human Urine in Hydroponic Lettuce (Lactuca sativa L.) Production. Sustainability 2023, 15, 10684. [Google Scholar] [CrossRef]

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© 2024 by the authors. Licensee MDPI, Basel, Switzerland. This article is an open access article distributed under the terms and conditions of the Creative Commons Attribution (CC BY) license (https://creativecommons.org/licenses/by/4.0/).

Correction: Mauerer et al. Replacing Mineral Fertilizer with Nitrified Human Urine in Hydroponic Lettuce (Lactuca sativa L.) Production. Sustainability 2023, 15, 10684

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