Irrigation-Water Management and Productivity of Cotton: A Review

Comment

Response

The authors have reviewed a substantial number of manuscripts from worldwide studies that is commendable.

The authors would like to thank the reviewer for the positive comments.

The format of the references is not consistent.

We thank you for this observation. The references of the manuscript have been now formatted according to the MPDI/Sustainability styles.

Texts in the tables (Ex Table 2) need a bit more formatting for the words.

The tables have been formatted as suggested by the reviewer.

It might be due to the conversion to PDF document, but it looks like the fonts are not consistent throughout.

Thank you. All the manuscript has been formatted.

Comment

Response

The authors provide a good review of irrigation management practices for cotton cultivation. This should be made clear at the onset of introduction to the paper. Perhaps the very title should read: A review of irrigation management practices for cotton cultivation.

The authors thank the reviewer for this comment. The authors refer to practices by using the words “management”. Therefore, they would like to keep the title as “Irrigation Water Management and Productivity in Cotton: A Review”.

Lines 40-45: Asia produces 15 million tons of cotton compared to 6.7 million tons by United States, but the authors mention that the United States is the leading exporter of cotton. Does Asia consume most of its production with not much export?

We thank the reviewer for this important question.

In the reference: # OECD/FAO (2019), “OECD-FAO Agricultural Outlook”, OECD Agriculture statistics (database). doi:dx.doi.org/10.1787/agr-outl-data-en. http://www.agri-outlook.org/commodities/Cotton.pdf

Page 218, Paragraph 2 it is revealed: “China remained the largest raw cotton consumer, accounting for around one-third of total spinning mill use…..”

In paragraph 4, the author of the chapter said: “Export growth was registered for the United States (the world’s main exporter),….”.

We understand that most Asia countries are raw cotton consumers.

Information provided in Table 1 could be reduced and better summarized.

The authors corrected Table 1, as you suggested

In Table 1:

For Farahani et al. (2008), instead of crop coefficient (Kc) of three years, we now use the average Kc values.

Likewise, for Bezerra et al. (2012), we use the average Kc values instead of two years Kc values.

Lines 148-150: what is the location for Evett et al. (2012) study?

In the book entitled “Crop yield response to water” of FAO Irrigation and Drainage Paper Number 66, Evett et al. contributed with a review on cotton. They mentioned that cotton being salt and drought tolerant is widely produced and its water use may range from 700 to 1 200 mm across the world.

Water use efficiency: lines 197-205 onwards:

The use of efficiency concept as it relates to water use and management is problematic. As originally defined and used in the thermodynamics sciences, the term efficiency compares input to the output of a machine and is expressed as a ratio or percentage. The authors’ definition of water use efficiency results in efficiency with units, which I am not very comfortable with. Several other studies have defined WUE as the ratio of crop ET and the amount of irrigation water. That way, at least the resulting term is a ratio and not with units.

If we want to compare crop production to the amount of water used, then why not call it ‘water productivity’?

The authors find this question interesting. Water use efficiency and water productivity are diversely understood. For some, they have the same meaning, while for others, they are different.

The authors would like to provide an understanding of Irrigation Efficiency, Water Productivity, and Water Use Efficiency.

The notion and concept of irrigation efficiency – defined as the ratio IE = [water beneficially used]/[total water applied] – is the traditional concept of efficiency in irrigation engineering.

The notion and concept of Water Productivity (WP) – defined here as the ratio (or unit) WP = [product]/[water consumed].

From the irrigation and water management perspective the notion of Water Use Efficiency (WUE) is introduced as a combination of the efficiency and productivity ratios. WUE is generally defined as: WUE = [product]/[water applied/available] – e.g. kg m^-3 or kg kg^-1.

Source: van Halsema, G.E., Vincent, L. (2012). Efficiency and productivity terms for water management: A matter of contextual relativism versus general absolutism.  Agricultural Water Management, 108:9-15. https://0-doi-org.brum.beds.ac.uk/10.1016/j.agwat.2011.05.016

Cotton yield and yield components in response to plant density, lines 425 onwards:

This section does not seem to relate to the main topic of irrigation water management.

We thank the reviewer for this important comment. They authors found plant density as an important practice that has a direct effect on crop water use, water productivity, water use efficiency, etc. Therefore, they would like to keep it in the review for its influence in the yield depending on the irrigation techniques used.

Comment

Response

This is a review manuscript covering different irrigation methods and their effects on cotton yield. The review considers the cotton crop coefficient and shows that the FAO-56 values are not appropriate for all regions, and local values need to be determined. The manuscript is interesting. It is written and organized very well. I did not find any scientific lack in this manuscript.

The authors would like to thank the reviewer for the positive comments on this review paper.