Effect of Different Water Quality on the Nutritive Value and Chemical Composition of Sorghum bicolor Payenne in Cape Verde

Round 1

Reviewer 1 Report

Authors evaluated the effect of reclaimed water (2 irrigation systems) into the nutritive value and chemical composition of Sorghum bicolor Payenne. However, limiting the scope of the paper to fodder quality and exclude any reflection on forage production (yields) and/or soil quality evolution (nutrient uptake and balance) reduce the potential impacts of the results and therefore the long term suitability of the technology proposed.

Introduction

Authors claim the importance of livestock in the country, but very little information about it is provided. Could you please include some details?

On a context of poor irrigation development (only 3500 ha), and probably a low prevalence of wastewater facilities, a more detailed description of the potential of “reuse practices” is missed in the introduction. How much water is treated and how much water could be used for irrigation in the country? Are there farming areas close to wastewater production (urban) areas?

Authors also claim the lack of water as a driver for wastewater reuse. However, checking the figures reported by FAO, the country is using less than 8% of their TRWR for irrigation. Could you please provide more details? Maybe lack of water infraestructures? Intra-annual variability? 

Regarding the aim of the project, it is difficult to understand that among the chemical/nutritional values, the authors are not investigating other crop productivity parameters, such as yields, water productivity, etc. What is the reason behind?

Lines 45-47 – The sentence is not well structured and it is hardly to understand

Material and methods

Line 87 – I find a 1 year experiment too short to get robust results. Can the authors provide more details about it?

Line 92 – can you provide more details about the fertilization applied (type of manure, nutrient content, etc).

Line 102 – why authors limit the experiment to 3 treatments instead of 4? I miss an extra treatment with conventional plus SFDI.

Line 107 – very little information about irrigation scheduling is provided. Where the information to feed CROPWAT is coming from (i.e. weather station)? Which parameters/methods you used to estimate irrigation requirements? How frequent do you re-calculate the irrigation scheduling (i.e. daily, weekly, monthly)? Do you apply the same water volume for both SDI and SFDI?

Line 115 – where the wastewater is coming from?

Line 118 and Table 1 – wastewater quality varies greatly, especially in small plants. Could you provide more details about the variation of the wastewater quality (i.e. range, standard deviation)? Some biological parameters are also key for wastewater reuse and there is no information in Table 1. What does SST means (TSS?)?

Line 119 – authors provide a very detailed description of the methods used for analyzing soil but a very poor description for water.

Table 1, 2 and 3 – Although authors provide a good characterization of water and soil, there is little discussion about it, specially comparing the values from reclaimed water and wells and the evolution of soil quality (pre manure, post manure, seeding and harvest). There are very little reference to those figures during the discussion. Authors may consider to move those tables (specially Table 3) to results and provide some insights about the evolution of soil properties and its relation with crop response.

Results and Discussion

Table 4 – During the discussion, authors refer to the maturity of plants (1 and 3 more mature and 2 and 4 less mature). However, from the reader point of view, this is difficult to understand, since this information was only provided in Material and Methods (number of days between cuttings), but without a reference to maturity. I will strongly suggest to include this statement in Material and Methods and also a reference of number of days between cuttings in the Table 4 itself (in brackets together with the harvest number).

Line 209 – where the RW came from? Is that B maybe related with (desalinated)sea water?

Line 223 – are those recommended ratios valid for all kind of livestock or specie specific?

Conclusions

Line 316-317 – This statement is not evaluated in the current paper “produced by a wastewater treatment plant adapted to a rural 316 village, with low energy use and maintenance costs”

Line 317 - This statement is not evaluated in the current paper “The installed SDI provided additional safety by avoiding contact between treated water and aerial plant parts”

Author Response

Dear Reviewer:
Thank you for your comments. We think  the text has been improved. A file is attached with a detailed response for all the comments. 
Best regards

Author Response File: Author Response.docx

Reviewer 2 Report

1. Section 2.1 requires additional clarification. As far as I understand, each of three blocks consists of 3 plots. If so, the use of the term "subplots" is inappropriate and suggests a “split-plot” type experimental design.   2. The observations for 4 successive harvests come from one experimental unit, and therefore their independence raises doubts. Please explain in detail. Has this fact been included in the analyzes? If not, what is the motivation?   3. Please specify if analyzes of variance or MANOVA - multivariate analysis of variance were performed, or if MANOVA command in SPSS for ANOVA was used.   4. The tables should be supplemented with the results of the analysis of variance. The model takes into account the interaction for (treatment * harvest), there is no information on its significance. For significant interactions, post-hoc testing should be performed for a combination of experimental factors and not for main effects. The results of tests of simple main effects should be considered suggestive and not definitive.   5. Editorial remark: the decimal separator in the entire paper - body text and tables - should be the same.

Author Response

Dear Reviewer:
Thank you for your comments. We think  the text has been improved. A file is attached with a detailed response for all the comments. 
Best regards

Author Response File: Author Response.docx

Round 2

Reviewer 2 Report

I am satisfied with the Aurors' responses and the corrections made to the manuscript.