Experimental Evaluation for the Impacts of Conservation Agriculture with Drip Irrigation on Crop Coefficient and Soil Properties in the Sub-Humid Ethiopian Highlands

Round 1

Reviewer 1 Report

The manuscript “Experimental evaluation for the impacts of conservation agriculture with drip irrigation on crop coefficient and soil properties in the sub-humid Ethiopian highlands” is review. The document present an interesting and valuable work, especially because is explained how is possible to do better agriculture practices combining conservation agriculture and drip irrigation low cost technologies, to improve water use and soil in regions with water scarcity and production problems.

However, there are some points that could be considered by authors in order to rewrite or justify some parts of the article:

1. Irrigation is done under farmers’ practice, and the “determine the irrigation frequency for their CA and CT plots”. This method suppose a reasonable strategy to compare management and practices, but it could have been complemented with a scientific control. In any case, and to compare CA and CT is needed to reference the final crop result, so, is needed to determine the crop production, biomass, canopy cover or some other crop parameter that allow determine if the results are comparable. Authors must justify this issue.
2. The kc value is obtained throw the soil water balance to obtain ETC and the reference crop evaporation by Penman-Monteith equation. This method is valid using lysimetric techniques; however, authors solve the balance by a TDR moisture measurement. Authors despite capillary rise, runoff and deep percolation beyond root zone, based on some references (51.52.53). The cited references do not consider these parameters because of they have other research purposes, deal whit other crops, climate and soils are very different; that allow this simplification, the cited references intention is not to calculate Kc. To ensure that Kc is properly obtained the soil balance must be done carefully, moreover, when irrigation water is deliver freely by farmers. However, the obtained coefficient (that cannot be named Kc, and a name change is suggested) is a valuable index to compare ET. Authors must reconsider, and better justify this issue.

Some other minor details must be pointed:

• The introduction describes the problem with a general scope helped with local references; although some of the references could be omitted because the argument is well known and founded.
• The experimental design section could be improved. It is clear that this manuscript supposes part of a bigger research and there are others works, e.g. Assefa (5) and Assefa et al (19) that support the data. Nevertheless the manuscript must be an independent work, so some schemes of the plot division, drip irrigation installations and stablish rotation could help to  better understand the experiment. By other hand, although pictures (figures 2-3) support the experiment description, could be reduced or changed by technical schemes.
• Lines 161-162. If tomato and garlic are not included in this paper, remove these lines or explain why are “data limitation”
• Lines 182-183. Explain the procedure to calibrate TDR probes
• Lines 259-26. Could be extended this justification?
• Figure 4. Why K is not represented?
• Figure 6. Legend must be arranged.
• Figure 7. To better understand the bars value a colour or weft change is suggested.
• Line 323. The single crop coefficient is used. The dual crop coefficient (FAO-56) could be introduced in this discussion; dual coefficient divide evaporation from transpiration, the main effect of CA is the evaporation reduction. The use of single coefficient is well justified, but enlarge the discussion talking about the dual scope could enrich and clarify what happen when a grass mulch is used (Take into account that is suggested clarify the coefficient Kc estimation, point B).
• Lines 344 -345 and figure 8. Coefficients obtained by Ayars and Glulik and Nyvall are both for garlic and cabbage simultaneously?

The manuscript reviewed has two problems (points 1 and 2) that could be solved; if authors correct these issues, the work shows how can be improved water use and soils by conservation agriculture and drip irrigation without expensive techniques or high budgets.

Author Response

Thank you very much for your constructive and useful comments. In the revised version, we tried to address all the comments provided by reviewers. All edits are provided using the “ track-change” in the revised manuscript.

Author Response File: Author Response.docx

Reviewer 2 Report

It's interesting the MS to bring together information about a field experiment consists of conservation agriculture (CA) and conventional tillage (CT) practices were set up in two areas, Robit and Dangishta, in sub-humid Ethiopian highlands. Paired¬‘t’ design was used for this experiment on a 100 m2 plot; where half of the plot was randomly assigned to CA and the other half to CT. A variety of vegetables including cabbage, garlic, onion, and pepper were grown at the study sites. Irrigation water use, soil moisture, and agronomic data were monitored, and laboratory testing was conducted for soil samples, which were collected from 0 to 40 cm depth before planting and after harvest during the study period of 2015-2017. Calculation of crop coefficient (Kc) revealed a significant decrease in Kc values under CA as compared to CT. The result depicted that CA with a drip irrigation system significantly ( = 0.05) reduced Kc values of crops as compared to CT. Specifically, 20% reductions were observed for onion, cabbage, and garlic under CA whereas 10% reductions were observed for pepper throughout the crop base period. Consequently, irrigation water measurement showed that about 18 to 28% of a significant irrigation water savings were observed for the range of vegetables under CA as compared to CT. On the other hand, the results of soil measurement showed the CA practice significantly ( = 0.05) increased soil moisture (4%, 7%, 8%, and 10% increment for onion, cabbage, garlic, pepper) than CT practice even if irrigation input was small in CA practice. In addition, CA was found to improve the soil phsico-chemical properties with significant improvement on organic matter (10%), field capacity (4%) and total nitrogen (10%) in Dangishta experimental site. CA with drip irrigation is evidenced to be an efficient water-saving technology while improving soil properties to support sustainable intensification in the region. I think that this study it is topical and contributes to improving specialized literature for which reason I As a suggestion, avoid long expressions
Please improve the discussion part.

Author Response

Thank you very much for your constructive and useful comments. In the revised version, we tried to address all the comments provided by reviewers. All edits are provided using the “ track-change” in the revised manuscript.

Author Response File: Author Response.docx

Round 2

Reviewer 1 Report

All the issues pointed in the first report have been sufficiently answered; changes in the new version clarify the methodology and results obtained.

There are some minor editing issues detected (non-exhaustive list):

Lines 106-118: text margins alignment

Line 205: final point

Line 274: final point

Line 364: double point

Line 420: figure 9 description is merged with discussion main text

Line 427: change final comma

A second review of “Experimental evaluation for the impacts of conservation agriculture…” is done. The document is improved and authors have taken into account the suggestions make in the previous evaluation. In my personal opinion, there are a weak point with the estimation of Kc coefficient, but authors arguments, based on previous research works, are enough.

Author Response

Thank you very much for your constructive minor edit comments. In the revised version, we have addressed all the minor edit comments provided for the manuscript. All edits are provided using the “ track-change” in the revised manuscript.