the Creative Commons Attribution 4.0 License.
the Creative Commons Attribution 4.0 License.
| 23 Jan 2023
Horizontal ridging with mulching as the optimal tillage practice to reduce surface runoff and erosion in a Mollisol hillslope
Abstract. Soil erosion features and ideal tillage practices are not very clear at the crop seedling stage in Chinese Mollisols. Simulated rainfall experiments were conducted at the rainfall intensities of 50 and 100 mm h-1 to investigate the differences in soil erosion of a 5° hillslope during the maize seedling stage between conservation and conventional tillage measures, including cornstalk mulching (Cm), horizontal ridging (Hr), horizontal ridging + mulching (Hr+Cm), vertical ridging + mulching (Vr+Cm), flat-tillage (CK), and vertical ridging (Vr). The results demonstrated that crops could remit soil erosion at the seedling stage by reducing the kinetic energy and changing the distribution of raindrops. The conservation tillage measures significantly alleviated total runoff (11.7 %–100 %) and sediment yield (71.1 %–100 %), postponed runoff-yielding time (85 s–26.1 min), decreased runoff velocity (71.5 %–96.7 %), and reduced runoff and soil loss rate, compared to the conventional tillage measures. Practices with mulching showed better performance than Hr. Mulching reduced sediment concentration (~70.6 %–100 %) by decreasing runoff velocity and soil particle filtration in a manner similar to buffer strips. The contour ridge ruptured earlier at 100 mm h-1 than at 50 mm h-1 and changed the characteristics of the soil erosion by providing a larger sediment source to the surface flow. Runoff strength, rather than soil erodibility, was the key factor affecting soil erosion. Decreasing runoff velocity was more important than controlling runoff amount. The Hr + Cm treatment exhibited the lowest soil erosion and is, thus, is recommended for adoption at the corn seedling stage in sloping farmlands.
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RC1: 'Comment on egusphere-2022-1526', Pedro Batista, 01 Feb 2023
General comments
The manuscript describes the influence of different tillage practices on surface runoff and soil erosion in Mollisol maize plots, based on rainfall simulation experiments in Northeast China. Although I see the value in the research topic, I do not think this manuscript is ready to be considered for publication in SOIL. There is simply not enough information in the methodology to allow for a proper assessment of results. There are also multiple inconsistencies which, in my opinion, compromise the scientific quality of the manuscript.
For instance, the authors state that their first objective is to “identify influence of maize seedling canopy on soil loss”. However, canopy cover was apparently not measured by the authors, or at least this was not reported. Moreover, although the manuscript seems to focus on crop seedling stages, there is no information regarding the timing of the rainfall simulations in relation to the crop stage. That is, the date(s) of the rainfall simulation(s) is(are) not provided, not even the number of days after sowing. There is also no information about the number of rainfall simulations performed per treatment, nor the number of plots per treatment. Hence, I do not know what the treatment means and error bars refer to in figures 4 and 5. This compromises the interpretation of the statistical analysis presented by the authors.
Furthermore, the authors report data on droplet size and kinetic energy for the rainfall simulations, but there is no information about how this data were measured. Besides the missing information, some of the methods seem unusual or lack justification (see detailed comments below regarding the “pre-rain” 24 hours before the experiments and the “drying of the topsoil layer”). In addition, I found some of the information presented in the introduction to be somewhat imprecise or not sufficiently supported by references.
These and several other issues are listed in the detailed comments below.
Detailed comments
Line 44: Please consider changing “soil layer thinning” to “soil thinning”.
Line 45: I suggest being more nuanced about crop yield losses associated to soil erosion (e.g., “and potentially to yield losses”).
Lines 46-48: Is the statement “Mollisol regions […] are the major crop producing areas globally” accurate? I could not find the reference you provided (i.e., Zheng, 2020).
Lines 50-51: What is total soil loss area?
Line 51: “Addressing soil erosion is important for soil loss reduction” seems redundant, please consider rephrasing.
Lines 58-60: These statements sound strange to me (perhaps I misunderstood something). As far as I know, a very substantial amount of research has investigated interactions between vegetation and soil erosion, including at early crop development stages.
Line 62: Sorry, which region?
Lines 61-63: I had a hard time understanding this. Are the rainfall simulation studies related to the ones during the rainy season? Also, which rainy season? For which region?
Line 67: Do you mean soil water holding capacity? How is Figure 1 illustrating this statement?
Lines 76-81: Please consider rewriting this paragraph.
Line 94: Could you please revise this sentence? By reading this I would understand the total soil depth is 30 cm, but I reckon this is not the case.
Line 102: I am not familiar with the term “agglomerate impurities” in this context. Could you please explain/reformulate?
Lines 103-106: Sorry, but I did not understand this part of the methods. Could you reformulate?
Line 107: Variety or cultivar?
Line 110: The “Flat-planting plots” had not been mentioned in the text yet, so I do not know what you are referring to here.
Line 122: How many plots?
Line 125: Are you sure that one hour of rainfall with 100 mm hr-1 intensity is representative of rainfall patterns in your study area?
Line 127: How many plots? When were the simulations performed? How many days after sowing? Do you have information on canopy cover and plant height?
Lines 127-130: How does pre-rain at 30 mm hr-1 for 5 min 24 hours before the experiments ensure consistent soil moisture?
Line 131: How did you dry the topsoil layer after the experiments? This sounds a bit odd, maybe I misunderstood something. Also, what do you mean by rainfall event? Do you mean the simulation? I am sorry, but I find your methods difficult to understand (description- and rationale-wise).
Line 151: As far as I understand, splash erosion would start as soon as the rainfall simulation begins. Moreover, how many rainfall simulations did you perform for each treatment?
Line 153: I found the statistical analyses difficult to understand without information regarding the number of plots and the number of rainfall simulations per treatment. That is, what are the “treatment means” you refer to? Also, what are the treatments? That is, how did you account for the interactions between tillage type, ridging direction, and rainfall intensities?
Lines 160-161: This is the first time you mention the measurement of raindrop energy and size distribution. How did you measure these? Shouldn’t this information be in the methods?
Lines 163-166: I found this very confusing. Please consider reformulating.
Lines 168-169: Do you think antecedent soil moisture might influence the time to the beginning of runoff?
Line 173: 23.8-fold is difficult to understand, please consider giving the actual time to runoff for the CK treatment.
Lines 174-175: Are these times to runoff referring to which rainfall intensity?
Lines 190-191: Did these low runoff amounts cause the rupture of the ridges? Is this correct?
Lines 197-198: Augmented the soil loss in comparison to CK?
Citation: https://doi.org/10.5194/egusphere-2022-1526-RC1 -
AC1: 'Reply on RC1', Yubin Zhang, 28 Feb 2023
The comment was uploaded in the form of a supplement: https://egusphere.copernicus.org/preprints/2023/egusphere-2022-1526/egusphere-2022-1526-AC1-supplement.pdf
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AC1: 'Reply on RC1', Yubin Zhang, 28 Feb 2023
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RC2: 'Comment on egusphere-2022-1526', Josef Krasa, 07 Feb 2023
I thank for the option to learn about interesting experiments.
I like the experiments, I like the goals, I like the focus of the authors on many variables in the study setup and the aim to use measured data to “explain”.
But without justifying the data was obtained “correctly” and with repetitions I cannot take the assumptions seriously and discuss on the results.
The experiment remains very poorly described, so the manuscript cannot be accepted in the present form without reworking the methods and results. In the entire manuscript there is completely unclear how was the setup concerning replicates. In several parts some repetitions are “pointed” (e.g. L131-133) but absolutely hiding the real approaches. There is no description on the statistics used to analyse the single experiments and produce presented values.
In many parts methods used to get the data in not explained (eg. drop sizes, distributions, KE, etc.).
Many graphs and tables are only vaguely described.
These and several other issues are listed in the detailed comments below.
Detailed comments:
L 23 – was this investigated directly, or is it authors’ assumption?
L 29 – comparison to buffers strips have no justification
L 63 – what is the relation of rainfall simulation experiment to rain seasonality concerning the results interpretation? I do not understand the statement.
L 93 – I assume from the figures it is a natural slope – so it was rather selected than set to? (even if I understand that the soil profile was created by added topsoil material) Or does not the Figure 1 refer to the experimental area? That is not clear from the figure 1, hence the Figure 2 looks like different area. Maybe to clarify the relevance of the figures for the experiment setup.
L 131 – 133: How the plots with maize could be restored the way you describe without affecting the vegetation. How many replicates could be done on the plots with vegetation. Or was it reseeded and used after longer period for replicates? Or were the replicates realized on other plots nearby? (The figure 2 does not look like) The whole process of plot maintenance and results replicability is very unclear.
L 136 – From he top? (not topsoil) How long plot section was used to estimate runoff velocity? 1m? What it means after it became steady? Was that always in the same minute? Or before the end of experiment?
L 141-142: I do not understand the sentence. What is the “runoff loss” in the context?
L 143 – delete “runoff rate”.
L 160 – 166: Where is the methodology section for these results? How the data was obtained? Missing techniques, setup, repetitions, durations, ….
L 292 – runoff initiation
L 298 Why then 100mm/h were in the study focus? 😊
L 322-325 One of the only sections raising questions on replicates, otherwise ignored in the whole text.
L 391-392: Contradictory to the statement in L 298
Concerning the discussion and conclusions, I did read it with interest, but before re-working the above sections, I do not want to rise my detailed comments here.
Figure 8: Y-axis: is it soil loss, or sediment yield as referred to in whole manuscript (kg).
What is the way (units, values) the residue cover is interpreted in the Figure 8 – that is totally unclear.
Figures 4-7: control, not contorl.
Citation: https://doi.org/10.5194/egusphere-2022-1526-RC2 -
AC2: 'Reply on RC2', Yubin Zhang, 28 Feb 2023
The comment was uploaded in the form of a supplement: https://egusphere.copernicus.org/preprints/2023/egusphere-2022-1526/egusphere-2022-1526-AC2-supplement.pdf
-
AC2: 'Reply on RC2', Yubin Zhang, 28 Feb 2023
Status: closed
-
RC1: 'Comment on egusphere-2022-1526', Pedro Batista, 01 Feb 2023
General comments
The manuscript describes the influence of different tillage practices on surface runoff and soil erosion in Mollisol maize plots, based on rainfall simulation experiments in Northeast China. Although I see the value in the research topic, I do not think this manuscript is ready to be considered for publication in SOIL. There is simply not enough information in the methodology to allow for a proper assessment of results. There are also multiple inconsistencies which, in my opinion, compromise the scientific quality of the manuscript.
For instance, the authors state that their first objective is to “identify influence of maize seedling canopy on soil loss”. However, canopy cover was apparently not measured by the authors, or at least this was not reported. Moreover, although the manuscript seems to focus on crop seedling stages, there is no information regarding the timing of the rainfall simulations in relation to the crop stage. That is, the date(s) of the rainfall simulation(s) is(are) not provided, not even the number of days after sowing. There is also no information about the number of rainfall simulations performed per treatment, nor the number of plots per treatment. Hence, I do not know what the treatment means and error bars refer to in figures 4 and 5. This compromises the interpretation of the statistical analysis presented by the authors.
Furthermore, the authors report data on droplet size and kinetic energy for the rainfall simulations, but there is no information about how this data were measured. Besides the missing information, some of the methods seem unusual or lack justification (see detailed comments below regarding the “pre-rain” 24 hours before the experiments and the “drying of the topsoil layer”). In addition, I found some of the information presented in the introduction to be somewhat imprecise or not sufficiently supported by references.
These and several other issues are listed in the detailed comments below.
Detailed comments
Line 44: Please consider changing “soil layer thinning” to “soil thinning”.
Line 45: I suggest being more nuanced about crop yield losses associated to soil erosion (e.g., “and potentially to yield losses”).
Lines 46-48: Is the statement “Mollisol regions […] are the major crop producing areas globally” accurate? I could not find the reference you provided (i.e., Zheng, 2020).
Lines 50-51: What is total soil loss area?
Line 51: “Addressing soil erosion is important for soil loss reduction” seems redundant, please consider rephrasing.
Lines 58-60: These statements sound strange to me (perhaps I misunderstood something). As far as I know, a very substantial amount of research has investigated interactions between vegetation and soil erosion, including at early crop development stages.
Line 62: Sorry, which region?
Lines 61-63: I had a hard time understanding this. Are the rainfall simulation studies related to the ones during the rainy season? Also, which rainy season? For which region?
Line 67: Do you mean soil water holding capacity? How is Figure 1 illustrating this statement?
Lines 76-81: Please consider rewriting this paragraph.
Line 94: Could you please revise this sentence? By reading this I would understand the total soil depth is 30 cm, but I reckon this is not the case.
Line 102: I am not familiar with the term “agglomerate impurities” in this context. Could you please explain/reformulate?
Lines 103-106: Sorry, but I did not understand this part of the methods. Could you reformulate?
Line 107: Variety or cultivar?
Line 110: The “Flat-planting plots” had not been mentioned in the text yet, so I do not know what you are referring to here.
Line 122: How many plots?
Line 125: Are you sure that one hour of rainfall with 100 mm hr-1 intensity is representative of rainfall patterns in your study area?
Line 127: How many plots? When were the simulations performed? How many days after sowing? Do you have information on canopy cover and plant height?
Lines 127-130: How does pre-rain at 30 mm hr-1 for 5 min 24 hours before the experiments ensure consistent soil moisture?
Line 131: How did you dry the topsoil layer after the experiments? This sounds a bit odd, maybe I misunderstood something. Also, what do you mean by rainfall event? Do you mean the simulation? I am sorry, but I find your methods difficult to understand (description- and rationale-wise).
Line 151: As far as I understand, splash erosion would start as soon as the rainfall simulation begins. Moreover, how many rainfall simulations did you perform for each treatment?
Line 153: I found the statistical analyses difficult to understand without information regarding the number of plots and the number of rainfall simulations per treatment. That is, what are the “treatment means” you refer to? Also, what are the treatments? That is, how did you account for the interactions between tillage type, ridging direction, and rainfall intensities?
Lines 160-161: This is the first time you mention the measurement of raindrop energy and size distribution. How did you measure these? Shouldn’t this information be in the methods?
Lines 163-166: I found this very confusing. Please consider reformulating.
Lines 168-169: Do you think antecedent soil moisture might influence the time to the beginning of runoff?
Line 173: 23.8-fold is difficult to understand, please consider giving the actual time to runoff for the CK treatment.
Lines 174-175: Are these times to runoff referring to which rainfall intensity?
Lines 190-191: Did these low runoff amounts cause the rupture of the ridges? Is this correct?
Lines 197-198: Augmented the soil loss in comparison to CK?
Citation: https://doi.org/10.5194/egusphere-2022-1526-RC1 -
AC1: 'Reply on RC1', Yubin Zhang, 28 Feb 2023
The comment was uploaded in the form of a supplement: https://egusphere.copernicus.org/preprints/2023/egusphere-2022-1526/egusphere-2022-1526-AC1-supplement.pdf
-
AC1: 'Reply on RC1', Yubin Zhang, 28 Feb 2023
-
RC2: 'Comment on egusphere-2022-1526', Josef Krasa, 07 Feb 2023
I thank for the option to learn about interesting experiments.
I like the experiments, I like the goals, I like the focus of the authors on many variables in the study setup and the aim to use measured data to “explain”.
But without justifying the data was obtained “correctly” and with repetitions I cannot take the assumptions seriously and discuss on the results.
The experiment remains very poorly described, so the manuscript cannot be accepted in the present form without reworking the methods and results. In the entire manuscript there is completely unclear how was the setup concerning replicates. In several parts some repetitions are “pointed” (e.g. L131-133) but absolutely hiding the real approaches. There is no description on the statistics used to analyse the single experiments and produce presented values.
In many parts methods used to get the data in not explained (eg. drop sizes, distributions, KE, etc.).
Many graphs and tables are only vaguely described.
These and several other issues are listed in the detailed comments below.
Detailed comments:
L 23 – was this investigated directly, or is it authors’ assumption?
L 29 – comparison to buffers strips have no justification
L 63 – what is the relation of rainfall simulation experiment to rain seasonality concerning the results interpretation? I do not understand the statement.
L 93 – I assume from the figures it is a natural slope – so it was rather selected than set to? (even if I understand that the soil profile was created by added topsoil material) Or does not the Figure 1 refer to the experimental area? That is not clear from the figure 1, hence the Figure 2 looks like different area. Maybe to clarify the relevance of the figures for the experiment setup.
L 131 – 133: How the plots with maize could be restored the way you describe without affecting the vegetation. How many replicates could be done on the plots with vegetation. Or was it reseeded and used after longer period for replicates? Or were the replicates realized on other plots nearby? (The figure 2 does not look like) The whole process of plot maintenance and results replicability is very unclear.
L 136 – From he top? (not topsoil) How long plot section was used to estimate runoff velocity? 1m? What it means after it became steady? Was that always in the same minute? Or before the end of experiment?
L 141-142: I do not understand the sentence. What is the “runoff loss” in the context?
L 143 – delete “runoff rate”.
L 160 – 166: Where is the methodology section for these results? How the data was obtained? Missing techniques, setup, repetitions, durations, ….
L 292 – runoff initiation
L 298 Why then 100mm/h were in the study focus? 😊
L 322-325 One of the only sections raising questions on replicates, otherwise ignored in the whole text.
L 391-392: Contradictory to the statement in L 298
Concerning the discussion and conclusions, I did read it with interest, but before re-working the above sections, I do not want to rise my detailed comments here.
Figure 8: Y-axis: is it soil loss, or sediment yield as referred to in whole manuscript (kg).
What is the way (units, values) the residue cover is interpreted in the Figure 8 – that is totally unclear.
Figures 4-7: control, not contorl.
Citation: https://doi.org/10.5194/egusphere-2022-1526-RC2 -
AC2: 'Reply on RC2', Yubin Zhang, 28 Feb 2023
The comment was uploaded in the form of a supplement: https://egusphere.copernicus.org/preprints/2023/egusphere-2022-1526/egusphere-2022-1526-AC2-supplement.pdf
-
AC2: 'Reply on RC2', Yubin Zhang, 28 Feb 2023
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