Effect of Tillage and Nitrogen Fertilization on Soil Properties and Yield of Five Durum Wheat Germoplasms in a Dry Area of Morocco

Round 1

Reviewer 1 Report

Effect of tillage and nitrogen fertilization on soil properties and yield of five durum wheat varieties in a dry area of Morocco
Main points
-    The tittle needs to be reviewed according to your main significant effect: why do you compared five wheat varieties? I feel that wheat yields are more important than soil data which seem questionable.
-    The Materials and Methods part is very poor and major points are missing:
o    A table giving the characteristics of the wheat varieties;
o    No idea on crop sampling methodology;
o    No idea on soil analyzing methodologies;
o    Did you record bulk density as suggest in the conclusion in line 274? No-tillage versus Conventional tillage comparison needs bulk density data (a lot of references showing that).
o    A clear explanation of the design, the tested factors tested is important; did you use a split-plot design? Is it a complete factorial randomized design?
-    The Results and discussion part need a deep improvement:
o    I recommend to begin by wheat data as it seems the most interesting point;
o    The tables: the tittles need to give more details and some data are questionable;
    table 1, when the soil data were recording? If only one value for NT and C, at the start of the experiment, it should be better to put that in the MM part;
    table 2, we need to know the number of data giving each standard deviation (n=?) and the number of years corresponding to the NT and CT comparison; the statistical significance of means comparison should be added by letters; total C is generally expressed in g kg^-1.
    table 3, same remarks as for table 2; a figure would be more appropriate; I wonder if total N expressed in % is organic N? Generally, it is organic N measured by a same analyzer (CHN) or separatly by Walkley-Black and Kjeldahl.
    tables 4 and 5, if you sum of ammonium and nitrate the first treatment i.e. NT N1 0-5 cm, it gives 0,105 in %; this value is high for mineral N, much higher than total N in table (0.07%). Generally, soil ammonium and nitrate are expressed in mg kg^-1; as ammonium is transitory form of nitrate, we could present the data by the sum of mineral N (ammonium and nitrate) and organic N.
o    The figures 2 and 3: as you separated CT and NT and you chose lines it not easy to read; bar charts with errors bars comparing both CT and NT for the five varieties and the three N inputs; a table needs to be added supporting this figure in giving the ANOVAs for grain and straw in testing the three different factors, tillage, variety and N input; we need each simple factor effect, the three interactions of each two-factor effect and the triple interaction.

Other details
Abstract:
-    L27-28: The last sentence of the abstract is vague; the term “In general” is not appropriate.
Introduction:
-    L31: the term “medium” is not appropriate.
-    L33-34: “Compared to other tillage practices, no-till provides several economic, environmental, and agronomic advantages”: moderate this affirmation; in some location no-till could provide advantages; permanent no-tillage adoption is not easy to define as well as to quantify.
-    L54-57: “The objective …”: the main hypothesis is not clear; why do you tested five varieties? Do you want to test the interaction between wheat genetic and soil environment?
-    L56: “germplasm”: different from a variety? Or new ones?
-    L77: “sowing type”: as you mentioned NT and NT, why naming this tillage factor “sowing type”? it should be more relevant to say “tillage type”.
Conclusions
-    I think that your objective could be to test the interaction of the five varieties under contrasted management?
-    L276-277: “In addition …”: this sentence could be transferred in the Results and discussion part.

Author Response

-

Author Response File: Author Response.docx

Reviewer 2 Report

Article: Effect of tillage and nitrogen fertilization on soil properties and yield of five durum wheat varieties in a dry area of Morocco

Line 27, 80 - what units are we talking about? The abstract appears in bibliographic databases as an autonomous text, it is necessary to specify the units in question.

Line 88 What was the result of the verification? What was the hypothesis verified. Please complete this. Two-way ANOVA was used. Please complete the.

Table 4. Adjust the order of the rows (NT, CT) to the order in the earlier tables

Figure 2, 3. Specify the units on the Y axis. The Y-axis numbers are probably dt / ha and the article uses t / ha. Please standardize it.

Line 218-220. Figures do not prove it. All values of N1, N2, N3 do not differ, they are within the error limits. Please provide the value of the F-test from ANOVA as given in chapter 3.1.2

There are no clear differences between the fertilization doses for the cultivars studied, which suggests examining other factors. Are there any studies on the root systems of these varieties? It is possible that the stress of water scarcity occurred, which prevented the plants from utilizing the N2, N3 dose. Maybe it is related to the anatomy of the root systems? It is worth developing these threads in the discussion.

Author Response

-

Author Response File: Author Response.docx

Reviewer 3 Report

 The manuscript used a field trial to study different N rates and genotypes combined with different tillage, the research could provide good infromation for durum sustainable production. Whereas, the results with one yield trial was no realiable, and the Tables and Figures need further improved，such as PPM, and lines could be repaced by bars in Figure 1-3.

Author Response

-

Author Response File: Author Response.docx

Reviewer 4 Report

The article suffers from the lack of appropriate statistical methods and relevant analyzes and it is better to be reanalyzed in this sense.

Author Response

-

Author Response File: Author Response.docx

Reviewer 5 Report

There is clarity in the approach to the problem and the results that seek greater efficiency in supplying chemical fertilizer to increase grain yield considering new no-till techniques. However, the overfertilization phenomenon is widespread, leading to a serious unbalance between the available nutrients the soil provides and the current demand for crops. The method and experimental design are straightforward and transparent and show innovation in implementing and analyzing fertilization strategies for durum wheat.

Author Response

-

Author Response File: Author Response.docx

Round 2

Reviewer 1 Report

Dear Authors and Editor,

As we did not receive point by point authors ‘remarks, thus it was difficult to do this second reviewing.
Thus, I began by giving my new remarks referring to the new manuscript and and attached I gave below point by point how authors reacted to my main first comments.

Main critical points
1. In substance
-    The abstract and the conclusion need a deep improvement.
-    L19: change by “a system that could improve cereal production thanks to soil fertility enhancement”.
-    L21 and L63: the soil fertility assessment needs to be added as an objective.
-    L23: give at the beginning results on soil analysis as in the text.
-    L23: “long-term”: give the number of years.
-    L24: add results on the two other varieties.
-    L30: change “In this research work” by “In conclusion”.
-    L107: Regarding the table 1, we need to have the source of the data and a sentence explaining the criteria used for these two other varieties; please add any information regarding the genetic variability of these five varieties.
-    L122-123: in a split-plot design, the interaction of the factor in sub-blocks and the block needs to be considered as a random factor in the model.
-    L368-L373: We know the objectives; so suppress these lines; begin in line 373 by “After 15 years, all the seven soil properties …”.
-    Discussion: Soil bulk density recording: no data were given; thus, the comparison on mineral soil data based on “content” and not “amount” of “No-tillage” versus “Conventional tillage” is an issue and needs to be discussed. Contrasted soil management should induce differences of bulk density at the top-soil.
-    In all figures and tables give in which year the data were recording.
-    In all tables add the standard deviation values using the symbol “±”.

2. In the form
-    In all figures suppress border lines and grids and add Y axis legend.
-    All number ≤ 10 need to be in full text e.g.  in line 59 “five durum wheat varieties”.

Thanks, Best regards.

Comments for author File: Comments.docx

Author Response

As we did not receive point by point authors ‘remarks, thus it was difficult to do this second reviewing.
Thus, I began by giving my new remarks referring to the new manuscript and and attached I gave below point by point how authors reacted to my main first comments.

There was something wrong as you did not receive our reply, point by point, to your comments. We submitted our replies to all the 5 reviewers via the website of the journal. The assistant editor (Ms Shae Han) informed us that replies to reviewers 1 and 3 were missing and asked us to attach them to an email and she will transfer them to the interested reviewers. We did it; but, unfortunately, you did not receive them. We are sending new (below) as well as old (in a separate file as supplementary material) replies to your comments.

Main critical points

1. 
   In substance
   
   

-    The abstract and the conclusion need a deep improvement.

The abstract was modified following the reviewer comments (L23 and L30 below); in particular, we added information about soil properties and yield for the two germoplasms. As these results were already presented in the ‘Conclusion’ section, we did not changed it.

-    L19: change by “a system that could improve cereal production thanks to soil fertility enhancement”.

The correction was done: the old sentence was replaced by this one.

-    L21 and L63: the soil fertility assessment needs to be added as an objective.

The correction was done: ‘soil fertility and’ was added before yield.

-    L23: give at the beginning results on soil analysis as in the text.

The following sentence was added to the abstract: ‘tillage type had a significant effect on soil organic carbon, CEC, ammonium, and nitrates while nitrogen dose had a significant effect on total nitrogen and nitrates. Regarding wheat yield, the results showed that’.

-    L23: “long-term”: give the number of years.

The correction was done: (15 years).

-    L24: add results on the two other varieties.

The correction was done: ‘whereas the the I.C and M.G germoplasms had 4.05 and 3.72 t ha^-1 of grain yield and 8.25 and 8.39 t ha^-1 of straw yield, respectively’ was added.

-    L30: change “In this research work” by “In conclusion”.

The correction was done: ‘In this research’ was replaced by ‘In conclusion’.

-    L107: Regarding the table 1, we need to have the source of the data and a sentence explaining the criteria used for these two other varieties; please add any information regarding the genetic variability of these five varieties.

The source of information about wheat varieties, a booklet of our institute INRA entitled ‘Nouvelles obtentions variétales INRA’, 2022, was added under the table. The other two varieties were chosen mostly for their resistance to diseases . We gave, in table 1, the most important information found in the booklet.

-    L122-123: in a split-plot design, the interaction of the factor in sub-blocks and the block needs to be considered as a random factor in the model.

Indeed, the block factor as well as its interactions with the other two (tillage type and soil depth) or three (tillage type, nitrogen dose, and either soil depth or wheat variety) factors were considered random; therefore, there were two different error terms for a split-plot design (soil properties assessed before the start of the trial) and three different error terms for a split-split-plot design (soil properties assessed at the end of the trial as well as wheat yields).

-    L368-L373: We know the objectives; so suppress these lines; begin in line 373 by “After 15 years, all the seven soil properties …”.

The correction was done: the first paragraph and the first sentence of the second paragraph were deleted.

-    Discussion: Soil bulk density recording: no data were given; thus, the comparison on mineral soil data based on “content” and not “amount” of “No-tillage” versus “Conventional tillage” is an issue and needs to be discussed. Contrasted soil management should induce differences of bulk density at the top-soil.

Unfortunately, we did not measure bulk density, we focused mostly on soil chemical properties.

-    In all figures and tables give in which year the data were recording.

The trial was done in the 2020-2021 cropping season (see, for example, 2.3. Experimental protocol when presenting when fertilizers were supplied) and harvest was done in summer 2021. So, we gave this information once a the ‘Material and methods’ section and did not repeat it in tables and figures.

-    In all tables add the standard deviation values using the symbol “±”.

Standard deviations were plotted, as error bars, in the different graphs and were deleted from all the tables.

2. In the form
   
   

-    In all figures suppress border lines and grids and add Y axis legend.
The corrections were done.

-    All number ≤ 10 need to be in full text e.g.  in line 59 “five durum wheat varieties”.

Corrections were done everywhere in the manuscript.

Author Response File: Author Response.docx

Reviewer 3 Report

  The manuscript had certain improved, whereas the presentation need more improved and the description  still no concise .  For example, Table 1 can be delete or replaced; P164, there was no significant interactions between  the two factors, what's the two factors? The author should not describe the results with no significant differences.

Author Response

In the original version of the manuscript, there was no such table on some features about wheat varieties. In fact, it was added following the recommendation of one of the 5 reviewers.  Moreover, it contains very useful information, especially about grain yield that allowed us to show that the cropping season experienced a strong water stress that prohibited nitrogen use efficiency thus leading to low grain yield compared to the normal performance of the wheat varieties. See in the manuscript, in the 3.2. Wheat yield result subsection, the paragraph starting with “Comparing values from Table 9 to those from Table 1, … it would have reduced the nitrogen use efficiency” as well as, in the conclusion section, the paragraph “There were no differences between tillage types and nitrogen doses and no interaction was significant. In particular, grain yields were low, similar to those possible in semi-arid area even though the study site is in the climatic favorable area. This is due mainly to water stress with rainfall shortage that reduced nitrogen use efficiency. ”, and, in the abstract, the paragraph “In addition, there were no effect of nitrogen dose due to water stress which reduced nitrogen use efficiency.”.

Regarding interactions, for soil properties measured before the experiment (3.1.2. Chemical properties), there were only two factors (tillage type and soil depth), results about these two factors were presented first before discussing their interaction, so the interaction was implicitly induced between these two factors and we also avoided repeating explicitly the name of these two factors. Moreover, for organic carbon, in the last sentence when explaining the absence of interaction, we explicitly named the two factors. The same applies for phosphorus when we explained the meaning of the presence of interaction. For soil properties measured at the end of the experiment (3.1.3. Total nitrogen, 3.1.4. Ammonium, and 3.1.5. Nitrate), there were three factors (tillage type, nitrogen dose, and soil depth). For example for total nitrogen, the last sentence indicates clearly what these three factors are even though they were explained before moving to their interactions. Finally, for grain and straw yield, none of the interactions between the two or the three factors (tillage type, nitrogen dose, and wheat variety) was significant.

Round 3

Reviewer 1 Report

Dear Authors and Editor,
Main point:
The temporal aspect is still confused and needs to be clarify in the abstract, materials and methods, conclusion parts and in the tittles of each table and figure. I suggest to put clearly when you did the measurement, and to precise after how many years the tillage techniques were applied, even it seems repetitive. Each table and each figure need to be individually well understood. Further, “Values are means over the three replications” could be replaced by “n=3”.
L 30: “These values are low for a favorable area and correspond to a semi-arid area”: I wonder if it would be more appropriate for the readers to know if these yields were favorable in your context in Morocco and semi-arid area context. In agronomy we are not necessarily looking for maximum yields but to the optimization of our crop cost interventions.
L 36: “grain yield values were lower due to a water stress”: same point as above; it would be on interest to select drought-resistant varieties; do you think that your rainfall pattern during this experiments is representative or not? As you applied this experiment during only one year, this point could be clearly discussed.
L79-80: “Soil samples were taken, using a hand auger, from both non-tillage (NT) and conventional tillage (CT) plots”; when?
L98: “wheat yield”: measured during one cropping season (2020-2021)? If true, give this information in the abstract, tittles of illustrations and in the conclusion.
L 139: table 2 tittle, add when these data were measured; before the start of the experiment as for table 3?
L159: “but” or “and”?
L382-383: “After 15 years, all the seven soil properties differed between depths with higher values at soil surface”; some information is missing; ““After 15 years, all the seven soil properties differed between depths with higher values at soil surface obtained under no-tillage.
L388: “Regarding wheat grain and straw yields”, recorded during the 2020-2021 cropping season.
L397: “The behavior of nitrogen dose is not regular”: dose and regular are not appropriate. Do you mean “N fertilization” and “variable between the tillage practices”?

Thanks. Best regards.

Author Response

Main point:

The temporal aspect is still confused and needs to be clarify in the abstract, materials and methods, conclusion parts and in the tittles of each table and figure. I suggest to put clearly when you did the measurement, and to precise after how many years the tillage techniques were applied, even it seems repetitive. Each table and each figure need to be individually well understood. Further, “Values are means over the three replications” could be replaced by “n=3”.

There were two times when measurements were made: before the start of the experiment and at the end of the experiment. These two times were already indicated in the materials and methods (2.2. Soil sampling and analysis, the 5^th sentence) as well as in tables 3, 4, and 6 and figures 2, 3, 4, and 5 and are now clearly indicated in the abstract, conclusion parts, and in the tittles of the remaining tables and figures.

It was already indicated, in the abstract, in the material and methods, and in the conclusion, the number of years of no-tillage is, in fact, 18 years) as it started in 2004 as indicated in the last sentence of 2.1 Study area. It is now added in the introduction (last section about objectives).

In tables and figures, ‘Values are means over the three replications’ was replaced by ‘(n=3)’.

L 30: “These values are low for a favorable area and correspond to a semi-arid area”: I wonder if it would be more appropriate for the readers to know if these yields were favorable in your context in Morocco and semi-arid area context. In agronomy we are not necessarily looking for maximum yields but to the optimization of our crop cost interventions.

The observed wheat yield values in your experiment were largely lower than what is commonly known for these varieties (see Table 1 and our discussion in 3.2. Wheat yield, especially the sentence beginning with ‘Comparing values from Table 9 to those from Table 1, …‘).  Our study area experienced the last three years a severe drought with much less rainfall compared to long term average and it would be a main factor that limited the nitrogen use efficiency, resulting in low wheat yield values. Unfortunately, we my experience another dry year as temperatures were as high as 32°C, two weeks ago, without rainfall. This is indicated when we presented and discussed grain yield in the Results section ‘Comparing values from Table 9 to those from Table 1, …‘.

L 36: “grain yield values were lower due to a water stress”: same point as above; it would be on interest to select drought-resistant varieties; do you think that your rainfall pattern during this experiments is representative or not? As you applied this experiment during only one year, this point could be clearly discussed.

Please, see our reply to the your comment just above.

L79-80: “Soil samples were taken, using a hand auger, from both non-tillage (NT) and conventional tillage (CT) plots”; when?

‘in September 2020’ was added.

L98: “wheat yield”: measured during one cropping season (2020-2021)? If true, give this information in the abstract, tittles of illustrations and in the conclusion.

We added ‘during the cropping season 2020-2021’ in the abstract, tittles of illustrations and in the conclusion.

L 139: table 2 tittle, add when these data were measured; before the start of the experiment as for table 3?

We added ‘measured before the start of the experiment’.

L159: “but” or “and”?
We replaced ‘but’ by ‘and’.

L382-383: “After 15 years, all the seven soil properties differed between depths with higher values at soil surface”; some information is missing; ““After 15 years, all the seven soil properties differed between depths with higher values at soil surface obtained under no-tillage.

We added ‘obtained under no-tillage’ as you recommended.

L388: “Regarding wheat grain and straw yields”, recorded during the 2020-2021 cropping season.

The modification was done indicating the time of measurement and the cropping season.

L397: “The behavior of nitrogen dose is not regular”: dose and regular are not appropriate. Do you mean “N fertilization” and “variable between the tillage practices”?

We replaced ‘not regular’ by ‘variable’.

Author Response File: Author Response.docx