Impacts of Biochar on Hydro-Physical Properties of Sandy Soil under Different Irrigation Regimes for Enhanced Tomato Growth
Round 1
Reviewer 1 Report
SPECIFIC COMMENTS
Lin 106: after text “CO3-2, HCO-3, and Cl- were determined by titration with acid and AgNO3” the word “respectively” must be included
Table 1: The title of the table is not self-explanatory enough. It could be improved by putting something like:Main properties of the soil saturated paste extract and the fresh and saline irrigation water.
Table 1 and Table 2: Haven't any of the measurements been repeated? It would be very interesting to know what the dispersion of the displayed values is.
Line 110 and 129: Excessive ")" in the text
2.4. Experimental layout: In general, the precise conditions of the work need to be defined, for example, it does not indicate whether the experiment has been carried out on a plot or in containers and it does not indicate the dimensions of these or those, if any, nor does it indicate whether it is an agricultural soil and if it has been subjected to irrigation or cultivation previously and for how long. Although in a previous section if it indicates the location, it would be necessary to indicate the classification of the soil or, failing that, a basic property such as texture or textural class, or at least the clay content and the type of clay, which are factors that are directly related to the soil water storage capacity.
Line 131-133: “Eighteen treatments were used in the greenhouse experiment to investigate the effect of date palm biochar at a rate of 4% (w/w). Nine of them were tested under deficit irrigation and other nine treatments were under partial root drying.” It is not clear how many treatments there are for each of the irrigation regimes, as it is expressed and as it appears in Table 3, it seems that the treatments of each type are 12 not 18. Please clarify.
Line 133-134: If possible, specify the origin of the saline water, whether it is natural water or if it is water prepared in the laboratory.
Table 3: This table can be improved. In the first place, it is unnecessary to repeat it in the treatments a – i if they are with fresh water or with saline water because it is already included in the lines that serve as title. On the other hand, while the text “Treatement with fresh water” is in a framed line above and below, the text corresponding to saline water is not and it would be better to unify the format.
On the other hand, the letters that are included only make it difficult to understand the experiment. The letters a-d are each for 2 treatments while e-i are for a single treatment and the same letter is used for both types of water and for both types of irrigation....very confusing indeed. The nomenclature used with symbols is much more intuitive and is sufficient. I propose to eliminate the letters and use the symbols
3. Results and Discussion.
The abbreviation used for deficit irrigation is sometimes used DI and the other RDI, please unify.
Figure 1 is incomplete, only some of the treatments a-d are shown and never of the same percentage. It would be interesting to see which occurs comparatively between biochar and without biochar for the same irrigation treatment. The same for Figure 2.
The title of the figures must be self-explanatory and both in Figure 1 and 2 it is incomplete.
On the other hand, the water deficit treatments are mixed in the same figure with those of PRD. It would be clearer to divide each figure in two.
Line 234: Does it mean that with biochar the plant consumes less water? Is there any evidence of this claim?
Line 236: These results refer to all treatments with biochar and without biochar? Possibly if percolation decreases, salinity increases when irrigation is reduced
The conclusions are clear, although they could be improved when the results are fully analyzed with the added suggestions.
Author Response
Reviewer 1
Comment: Line 106: after text “CO3-2, HCO-3, and Cl- were determined by titration with acid and AgNO3” the word “respectively” must be included
Response: Needful done
Comment: Table 1: The title of the table is not self-explanatory enough. It could be improved by putting something like: Main properties of the soil saturated paste extract and the fresh and saline irrigation water.
Response: Needful done
Comment: Table 1 and Table 2: Haven't any of the measurements been repeated? It would be very interesting to know what the dispersion of the displayed values is.
Response: Tables 1 and 2 they display the values of main properties of material which were used in the experiments such as soil, kind of water and biochar, and no need to repeat the measurements.
Comment: Line 110 and 129: Excessive ")" in the text
Response: This is the description of the biochar used in the experiment and the details are needed in the text.
Comment: 2.4. Experimental layout: In general, the precise conditions of the work need to be defined, for example, it does not indicate whether the experiment has been carried out on a plot or in containers and it does not indicate the dimensions of these or those, if any, nor does it indicate whether it is an agricultural soil and if it has been subjected to irrigation or cultivation previously and for how long. Although in a previous section if it indicates the location, it would be necessary to indicate the classification of the soil or, failing that, a basic property such as texture or textural class, or at least the clay content and the type of clay, which are factors that are directly related to the soil water storage capacity.
Response: Some details of soil in table 1, and the soil in greenhouse was subjected to previous cultivation. Soil texture was added in table 1. The dimension of each unit 1 X 7 m2.
Comment: Line 131-133: “Eighteen treatments were used in the greenhouse experiment to investigate the effect of date palm biochar at a rate of 4% (w/w). Nine of them were tested under deficit irrigation and other nine treatments were under partial root drying.” It is not clear how many treatments there are for each of the irrigation regimes, as it is expressed and as it appears in Table 3, it seems that the treatments of each type are 12 not 18. Please clarify.
Response: Certainly, the number of treatments were eighteen, nine of which were with fresh water and the other with saline water. For fresh water, the deficit irrigation treatments were repeated at irrigation levels 100, 80, 60 and 40% with biochar e.g. (DIF- B100) and without biochar (DIF100) addition to the full irrigation and partial irrigation treatments. The saline water, partial root drying treatments were repeated with biochar (SPRD-B1) and without biochar (SPRD1) in growth stages, addition to the full irrigation treatment (SPRD-B100) and deficit irrigation (SDI100, 80, 60 and 40%).
Comment: Line 133-134: If possible, specify the origin of the saline water, whether it is natural water or if it is water prepared in the laboratory.
Response: The saline water was prepared.
Comment: Table 3: This table can be improved. In the first place, it is unnecessary to repeat it in the treatments a – i if they are with fresh water or with saline water because it is already included in the lines that serve as title. On the other hand, while the text “Treatement with fresh water” is in a framed line above and below, the text corresponding to saline water is not and it would be better to unify the format.
Response: The treatments were different; the format was modified.
Comment: On the other hand, the letters that are included only make it difficult to understand the experiment. The letters a-d are each for 2 treatments while e-i are for a single treatment and the same letter is used for both types of water and for both types of irrigation very confusing indeed. The nomenclature used with symbols is much more intuitive and is sufficient. I propose to eliminate the letters and use the symbols
Response: The letters beside the names of the treatments to clarify the treatment of soil water distribution and salinity distribution in figure 1 to 4.
- Results and Discussion.
Comment: The abbreviation used for deficit irrigation is sometimes used DI and the other RDI, please unify.
Response: The abbreviations were unified.
Comment: Figure 1 is incomplete, only some of the treatments a-d are shown and never of the same percentage. It would be interesting to see which occurs comparatively between biochar and without biochar for the same irrigation treatment. The same for Figure 2.
Response: Yes, indeed, only selected treatments were presented as other have not significant effect.
Comment: The title of the figures must be self-explanatory and both in Figure 1 and 2 it is incomplete.
Response: It has been modified
Comment: On the other hand, the water deficit treatments are mixed in the same figure with those of PRD. It would be clearer to divide each figure in two.
Response: Our aim was evaluating soil moisture distribution under different irrigation methods with kinds of water.
Comment: Line 234: Does it mean that with biochar the plant consumes less water? Is there any evidence of this claim?
Response: We do not mean that, but the high salinity in the last stage may be due to the accumulation of salts as a result of saline water with biochar.
Comment: Line 236: These results refer to all treatments with biochar and without biochar? Possibly if percolation decreases, salinity increases when irrigation is reduced.
Response: In this case irrigation water was saline, that mean when irrigation is reduce by deficit methods the salinity was decrease.
Comment: The conclusions are clear, although they could be improved when the results are fully analyzed with the added suggestions.
Response: Thank you.
Author Response File: 
Author Response.docx
Reviewer 2 Report
Are the growth stages associated with the developmental stages of the plant?
line 167: what is the mathematical representation of equation 2?
Author Response
Reviewer 2
Comment: Are the growth stages associated with the developmental stages of the plant?
Response: Yes
Comment: line 167: what is the mathematical representation of equation 2?
Response: That means the equations in Appendices 1
Author Response File: Author Response.docx
