Review Reports - Sheep Excrement Increases Mass of Greenhouse Gases Emissions from Soil Growing Two Forage Crop and Multi-Cutting Reduces Intensity

Round 1

Reviewer 1 Report

The article has been properly prepared. Most importantly, is that article includes the literature from solid sources.

The correlation was done properly.

I am not making any major comments, but the authors should expand their conclusions. No values from results have been specified in the conclusions, this should be improved.

Author Response

Dear reviewer 1:

It is our very honour to revise the manuscript following your directions. Combined with your suggestions, we intend to submit revised vision with great respect after a lot of discussion and rigorous revision, and we wish the manuscript would be suitable for publication in Agriculture. We used the "Track Changes" function in Microsoft Word so that they were easily visible to the editors and reviewers. We have responded to your comments sincerely:

Point 1: The article has been properly prepared. Most importantly, is that article includes the literature from solid sources. The correlation was done properly. I am not making any major comments, but the authors should expand their conclusions. No values from results have been specified in the conclusions, this should be improved.

Response 1: Thank you very much for your directions. We have refined the conclusions to include key values from results:

Line 447-454: This study showed that sheep excrement changed the CH₄ sink into a CH₄ source and increased the CO₂ and N₂O emissions in the soil of common vetch and spring wheat, and it contributed 94.65% and 44.58% to GWP in both soils at the same time. Whereas multi-cutting significantly reduced the GHGI of two forage crops to 37.51% and 35.09%, respectively, and promoted the growth of forage crops. Future studies should consider the spatiotemporal effects of cutting and sheep excrement on GHG emissions in order to improve the prediction of future climate impacts resulting from grazing activities.

We would be very grateful if the submitted manuscript could be considered for publication in Agriculture. Everything goes well!!

Your kind considerations will be greatly appreciated.

With best regards.

Sincerely Yours.

Reviewer 2 Report

The study report interesting finding about the greenhouse gas. In revision the experimental method and results are clear. Discussion is almost reasonable.

Minor suggestion- Line no 435-436-Cite with ref. https://doi.org/10.1007/s11157-020-09554-w along with ref. 27-45.

Author Response

Dear reviewer 2:

Point 1: The study reports interesting finding about the greenhouse gas. In revision the experimental method and results are clear. Discussion is almost reasonable. Minor suggestion- Line no 435-436-Cite with ref. https://doi.org/10.1007/s11157-020-09554-w along with ref. 27-45.

Response 1: Thank you very much for your directions. We have carefully read and studied the ref. https://doi.org/10.1007/s11157-020-09554-w, which is very valuable and helpful to us. We have cited this paper in the discussion:

Line436-438: The anaerobic environment in the soil provided favorable conditions for denitrification, and the nitrogen in sheep excrement provided sufficient substrate for denitrification [27,45,46].

Line589-591: 46. Kumar, A.; Medhi, K.; Fagodiya, R.K.; Subrahmanyam, G.; Mondal, R.; Raja, P.; Malyan, S.K.; Gupta, D.K.; Gupta, C.K.; Pathak, H. Molecular and ecological perspectives of nitrous oxide producing microbial communities in agro-ecosystems. Rev Environ Sci Bio 2020, 19, 717-750, doi:10.1007/s11157-020-09554-w.

We would be very grateful if the submitted manuscript could be considered for publication in Agriculture. Everything goes well!!

Your kind considerations will be greatly appreciated.

With best regards.

Sincerely Yours.

Reviewer 3 Report

This article deals with greenhouse gas from sheep excrement in soil, agricultural system.

Line 44-46. More specific definition, method of multi cutting information seems to be described for readers.

Line 90. the unit of EC seems to be edited (not %, ds/m or us/cm, etc.)

Line 119. The box means chamber? Why author used "box" rather than chamber which is much more common term.

Author Response

Dear reviewer 3:

Point 1: This article deals with greenhouse gas from sheep excrement in soil, agricultural system. Line 44-46. More specific definition, method of multi cutting information seems to be described for readers.

Response 1: Thank you very much for your directions. We have detailed the specific definition and method of multi-cutting:

Line44-47: Multi-cutting, which is often considered as a simulated grazing method by cutting the stem of forage crops frequently with harvesters [6,7], can not only significantly reduce plant overground but also affect soil nutrient cycling, thus altering soil GHG emissions [8].

Point 2: Line 90. the unit of EC seems to be edited (not %, ds/m or us/cm, etc.)

Response 2: Thank you very much for your directions. We are very sorry for the error of the unit of EC and have corrected it to mS/cm after checking the original data:

Line 89-93: The soils were categorized as Aquisalids on the basis their 0.7–0.9% salt content [1,22], soil pH was 8.06±0.09, the soil electrical conductivity was 2.87±0.03mS/cm, soil organic carbon content was 8.06±0.31g/kg, soil total nitrogen content of 0.87±0.02g/kg, and soil total phosphorus content of 0.53±0.01g/kg (unpublished data).

Point 3: Line 119. The box means chamber? Why author used "box" rather than chamber which is much more common term.

Response 1: Thank you very much for your directions. We are very sorry for our error. We have changed box to chamber and conducted a thorough check to make sure that others are correct:

Line120-146: CH₄, CO₂, and N₂O were collected and analyzed using a static chamber and gas chromatograph [25]. The chamber body featured an opaque darkroom with a size of 30 cm × 30 cm × 30 cm. Except for the opening at the bottom, all other sides were sealed, and the outer layer was sealed with a foam plate approximately 2.5 cm thick. The top of the chamber was connected with a thin tube approximately 30 cm long with an inside diameter of 1 cm. Before collecting the gas, we prepared a tray approximately 50 cm long and wide, and we moved the pot to the tray and covered the gas chamber before filling the tray with enough water to seal the chamber. When collecting greenhouse gases, three-way valves and 50 mL syringes were used to collect gas from the static chamber and transfer it to an air bag with a capacity of approximately 500 mL, which was then taken back to the room to analyze the concentrations of the gas components. The gas was collected at 0, 10, 20, and 30 min after each treatment between 9:00 a.m. and 11:00 a.m. The gas emission fluxes collected during this period are considered to represent the mean gas emissions per day. The static chamber collected four air bags at a time, and each set of collections was repeated three times. The concentrations of CH₄, CO₂, and N₂O were analyzed and measured using a gas chromatograph (GC-2014CC11885530256, produced by Shimadzu Company of Japan). The emission fluxes of the three gases were calculated as follows [26,27]:

where F(GHG) represents the emission value of each greenhouse-gas (mg·m⁻²·day⁻¹ or μg·m⁻²·day⁻¹), ρ represents the density of the gas to be measured under standard conditions (CH₄ = 0.717 kg·m⁻³, CO₂ = 1.977 kg·m⁻³, N₂O = 1.978 kg·m⁻³), V represents volume of the static chamber (0.027m³), R represents radius of pot (0.15m), P represents the atmospheric pressure at the sampling site (kPa), and P₀ represents the standard atmospheric pressure (P₀ = 101.325 kPa). T₀ represents the absolute temperature under standard conditions (T₀ = 273.15 K), T represents the temperature (K), and dCt/dt represents the change rate of gas concentration over time.

We would be very grateful if the submitted manuscript could be considered for publication in Agriculture. Everything goes well!!

Your kind considerations will be greatly appreciated.

With best regards.

Sincerely Yours.

This manuscript is a resubmission of an earlier submission. The following is a list of the peer review reports and author responses from that submission.

Round 1

Reviewer 1 Report

The manuscript entitled “Sheep Excrement Increased Greenhouse-Gas Emissions of Soil Growing Two Forage Crops and Multi-Cutting Reduced Greenhouse-Gas Intensity” has been critically reviewed. Greenhouse gases monitoring and their potential emission reduction is highly required in climate change scenario. This manuscript have scientific merits in respect of climate change. This paper not only provides the valuable insights of the global audience but also support to address the environmental biologist to identify the solution for the mitigating the greenhouse form grassland ecosystems. Before considering this manuscript further kindly consider few point wise comments and updating manuscript.

Introduction:

Kindly use full name before using abbreviation, for example –In first line of manuscript, the increase in greenhouse gas (GHG, including mainly CO2, N2O, and CH4 [1]) emissions has aggravated global warming, which has become a concern for society.

Kindly write carbon dioxide (CO2), nitrous oxide (N2O), so soon.

Reference no 1 is very old, replace with recent study.

Material and Methods:

2.1 Kindly add phyico-chemical properties of the soil, like pH. EC, SOC, etc.

2.2 write scientific name of wheat and common vetch

Kindly describe Control treatment, what it is??? Without cutting or sheep excrement or without plant??????

2.3 Sampling and analysis

Authors wrongly calculated the GHG flux,

V represents the bottom area of the box (0.09 m2), A represents the height of the box (0.3 m),

V is volume of static box not bottom area, and A will be area of pot in m². Kindly correct it re-calculated flux, followed by GWP and GHGI.

Result

3.2.1 CO2 emissions –split CO2 emission in further two subsection-----

3.2.1.1 CO2 emission from common vetch and

3.2.1.2 in CO2 emission from spring wheat.

3.2.2 N₂O emissions –split into further subsection –

3.2.2.1 N2O emission from common vetch and

3.2.2.2 N2O emission from wheat

3.2.4 Kindly cross check the unit of GWP

Add line number in manuscript it will easily for reviewer.

Reviewer 2 Report

Footnote 4 about "Grazing livestock contributes to 17%" is very old and dates from 2005, and a lot has changed since then.

As for the Introduction, I recommend that the authors read the article I cited below because it is about the topic the authors describe. In particular, the authors write (there are few studies on the emissions of different components) in the paragraph before chapter 2.

Roman M., Roman M., Roman K.K. (2019): Spatial differentiation of particulates emission resulting from agricultural production in Poland. Agric. Econ. – Czech, 65: 375-384.

The charts are very unreadable.

In order to obtain correlations within the scope of the statistical analysis, some post-hoc test (eg Duncan test) would have to be performed. This will allow you to group the results into homogeneous groups and discuss them.