In-Field Rainwater Harvesting Tillage in Semi-Arid Ecosystems: II Maize–Bean Intercrop Water and Radiation Use Efficiency

Round 1

Reviewer 1 Report

There is no description or definition of the two main effects, CON and IRWH.  You cannot assume that all readers are familiar with the types of production used here.  The paper is far to long for the amount of information presented.  Most of the figures and tables are superfluous. 

Author Response

Dear Reviewer

Comments:

There is no description or definition of the two main effects, CON and IRWH.  You cannot assume that all readers are familiar with the types of production used here.  The paper is far to long for the amount of information presented.  Most of the figures and tables are superfluous. 

Response:

The authors are working to improve the MS. 

• The two tillage systems (CON and IRWH) are described in both the introduction and methodology sections.  And clearly abbreviated on both the abstract and the main text body.
• The paper is quite long, but the main reason for using many results from the farmer's field measurements that demonstrate the difference in two villages with different soils under different tillage systems as well as cropping systems. The authors agree to present results from growth, Yield, BM and PUE parameres, etc. This will help to explain the practical measurement from on-farm demonstration plots while farmers participated and engaged in the project/study directly. This is clearly explained in the study site description and farmers' selection on the study.
• All editorial corrections are done and improved the abstract section and revise the whole conclusion section.
• Please see attached some major changes made to the MS. And some editorial language corrections are made in the MS.

Thank you!

Author Response File: Author Response.docx

Reviewer 2 Report

Line # 14- Don’t abbreviate for intercropping

Line 14: use word in-situ moisture conservation in place of in-field rainwater harvesting

Line 16 consistent use terminologies line 17 and 18 use either plot or treatment for example treatment vs plot, solely v/s sole; beans sole vs sole beans

Line 24 delete solely grown maize replace with sole maize

Line 25 and 26 revise sentence

Line 28 are replaced with were

Line 32 radiation use efficiency replaced by RUE since it is already abbreviated in line 20.

Line 32,33 and 34 delete entire sentence

Arrange key words according alphabet

Throughout the text replace in-field word with In-situ

Line 60 cite recent reference

Line 72 delete radiation use efficiency replaced by RUE since it is already abbreviated in line 20.

Sentence is incomplete Iine 72 and 73

Line 78 CON is already abbreviated in line #17

Revise last paragraph of introduction for meaningful sentences

Line 178 delete the word ‘in the wavelength’

Delete sentence 232- 233

Delete sentence in 312- 314.

Line # 331 Delete word secondly

Quote cite for maize and beans growth phases (Line #353- 358).

Mention line quantum sensor manufacturer name and product number; is it one meter length

Mention the indication of TLM and hm

Statistical analysis part is missed in the text.

Table 3 footnote expand AGDM, Yg

Give proper reasons for Fig.5 intercepted PAR in sole maize was higher than intercropping?

In general intercropping LAI will be more than sole crop.

Table 4 RUE % improve, is it over sole maize or sole beans?

RUE of maize is too low?

Citation missing in reference section Monteith in Line #213

Ndakidemi, 2006 should be as Ndakidemi et al., 2006

Line 73 sadras et al. 2006 should be replaced with Sadras (2006)

Sinclair 1983, missed in reference section

Line 688 Tsubo et al., 2004 should be written as Tsubo and walker 2004

Line 337 Walker and Tsubo 2003a missed in reference

Discussion section should be improved with proper data and % improvement in intercropping over sole crops.

Line # 659 is contradicting to your results sole maize and intercropped maize.

 

Conclusion is too elaborative try to be in precise, avoid quoting figure numbers, references in the conclusion

 

References

Reference 3, 12, 18, 20, 24, 28, 29, 41, 53 were not found in text

Reference 47 repeated

Reference 49 and 51 authors and year are same; separate them by ‘a’ and ‘b’

Author Response

Reviewer #2 comment Response

Line # 14- Don’t abbreviate for intercropping

- Response: On the abstract: deleted "(Ic)

Line 14: use the word in-situ moisture conservation in place of in-field rainwater harvesting

- Response: The term IRWH = is a common name known in dryland farming for smallholders to harvest water from in-field to minimize avoid runoff. So it is difficult to use the in-situ moisture conservation

Line 16 consistent use terminologies line 17 and 18 use either plot or treatment for example treatment vs plot, solely v/s sole; beans sole vs sole beans;

- Response: deleted and changed to plot and sub-plot

Line 24 delete solely grown maize replace with sole maize:

- Response: changed accordingly except in a few sentences to fit in to make specification.

Line 25 and 26 revise sentence: 

- Response: It is rephrased as "The RUE under IRWH tillage was estimated to be 0.65 and 0.39 g DM MJ^-1, in sole maize and intercropping respectively.

Line 28 are replaced with were

Line 32 radiation use efficiency replaced by RUE since it is already abbreviated in line 20.

- Response= Corrected by "RUE"

Line 32,33 and 34 delete entire sentence:

- Response = Deleted the sentence and rephrased the following sentence

Arrange key words according alphabet:

- Response = re-arrange the key words accordingly "

Keywords: Evapotranspiration; radiation interception; radiation use efficiency; soil water balance; water productivity

Throughout the text replace in-field word with In-situ: 

- Response: In this study, it seems inappropriate to change the terminology as it is known as IRWH for the 2-3 decades in this type of environment in SA. But Explained in methodology the stsrucut=re and explained in the above.

Line 60 cite recent reference:

- Response: well taken comment In general the introduction section is modified by updating the references and adding relevant background information (see the highlight sections)

Line 72 delete radiation use efficiency replaced by RUE since it is already abbreviated in line 20.

- Response: replaced as "RUE"

Sentence is incomplete Iine 72 and 73

- Response: rephrased and added verb 

Line 78 CON is already abbreviated in line #17

- Response = corrected as "CON"

Revise last paragraph of introduction for meaningful sentences:

- Response: The whole paragraph is repharsed and changed and the last sentence is changed as: "This study, therefore, hypothesizes that maize-bean intercropping under the Improved tillage (IRWH) system increases resource productivity and efficiency compared to solely grown crops. Additionally, there are positive relationships between WP and RUE in both IRWH and CON tillage systems, with higher water deficit and lesser available radiation use in CON compared to IRWH."

Line 178 delete the word ‘in the wavelength = it is deleted ’

Delete sentence 232- 233 = deleted 

Delete sentence in 312- 314. = Deleted 

Line # 331 Delete word secondly = deleted and rephrased

Quote cite for maize and beans growth phases (Line #353- 358).

- Response = It is referenced as" 

The growth stages of the maize and beans described in this study are almost identical to other previous studies (for example that reported by FAO: Doorenbos and Kassam, 1986; FAO, 2000). For both crops, the growth stages can be divided into four phases:

• For maize - GS-1 = initial vegetative phase, GS-2 = active vegetative phase, GS=3 initial grain-filling phase, and GS-4 = active grain-filling phase.
• For beans – GS-1 = emergence and early vegetative growth, GS-2 branching and rapid vegetative growth, GS-3 = flowering & pod formation and GS-4 = pod fill and maturation

Mention line quantum sensor manufacturer name and product number; is it one meter length

- Response: Addedd - the model and manufacturer "(Kipp & Zonen model PQS 1, LI-COR models LI-190)"

Mention the indication of TLM and hm

- Response: Where T_LM is the total maize leaf area, and  h_M and h_B are the height of maize and beans canopy."Response : It has already indicated "

Statistical analysis part is missed in the text.

- Response: Added the following as statisy=tical analysis

Analysis of variance (ANOVA) was done for the comparison of different treatments using SAS 9.1.3 for Windows (SAS Inst Inc., 2006). When the significance of the treatment on the F-statistic is mentioned, it refers to a comparison using the least significant differences (LSD) at the 0.05 probability level. In the study, a relationship between RUE and WP was analyzed as the slope of the linear regression using aggregated data from the two locations for different cropping systems under different tillage to understand the effect of available soil water for productivity and the atmospheric demand in the semi-arid crop production system."

- Response: 

Table 3 footnote expand AGDM, Yg =

- Response: Added and corrected all GY and changed to Yg = for grain yield.

Give proper reasons for Fig.5 intercepted PAR in sole maize was higher than intercropping.

In general intercropping LAI will be more than sole crop.

Table 4 RUE % improve, is it over sole maize or sole beans?

Response: Added in the methodology about Change in RUE:

Where W_B and W_M are dry matter (in kg) for beans and maize, respectively and I_o is the incident radiation in (MJ m^-2 d^-1).  Comparative change in RUE was calculated according to Morris and Garrity (1993) to relate productivity across varying intercropping periods and densities (D). The indice was based on relative rather than absolute values. Change in RUE was calculated based on dry matter as shown in equation 13.

see equation 13 in the text

where X is RUE, P_m is the proportion of maize in intercrop, P_b is the proportion of beans in intercrop, subscripts Ic is intercrop, sm is sole maize, and sb is sole beans. Proportions of maize and beans in the intercrop, given by P_m = D_m/(D_m + D_b) with D_m and D_b being the density in intercropping relative to sole cropping of maize and beans, respectively. For interpretation, when Δ’s greater than zero, are assumed to be higher in the intercrop system relative to the sole crop.

RUE of maize is too low? 

Response: Yes I agree but the main reason is the spacing of maize under IRWH is wide as included in the empty runoff section which makes the RUE very low. In addition as dry; and farming the plant population is very low (only 18,000/ha). Thus it is expected lower values.

Citation missing in reference section Monteith in Line #213 = corrected

Ndakidemi, 2006 should be as Ndakidemi et al., 2006 = corrected

Line 73 Sadras et al. 2006 should be replaced with Sadras (2006) = corrected

Sinclair 1983, missed in reference section = corrected

Line 688 Tsubo et al., 2004 should be written as Tsubo and walker 2004 = corrected

Line 337 Walker and Tsubo 2003a missed in reference = corrected

Discussion section should be improved with proper data and % improvement in intercropping over sole crops.

- Response: As suggested the discussion section is re-arranged and some sections are moved from the result section and corrected accordingly. see the new discussion section in the text.

Line # 659 is contradicting to your results sole maize and intercropped maize.

- Response:- Deleted and corrected the contradictory statement but the authors presented the findings for each village with some inconsistent results for IRWH-S- M during 38-70 DAE and for IRWH -S-B at the later stage (70-96 DAE). As the experiment was conducted during dry season there was some variation in selling emergence and growth etc.

 

Conclusion is too elaborative try to be in precise, avoid quoting figure numbers, references in the conclusion

• Response: the whole conclusion is re-write again and edited as:

Improving rainfed crop production per unit area for smallholder farmers during the short rainy season is crucial for achieving food and nutrition security. In semi-arid regions, where dry conditions (El Niño seasons) and long dry spells are common due to climate change, farmers are exploring alternative techniques to increase water productivity and use resources more efficiently. Using water harvesting techniques on marginal land can help reduce the pressure to produce grain in less productive and environmentally fragile agroecosystems. The Thaba Nchu rural community faces low productivity and needs improved techniques. However, there is poor adoption of these techniques and disorganized intercropping due to water scarcity in arid and semi-arid areas. This highlights the need for alternative techniques that increase smallholders’ productivity through the ability to capture and use resources more efficiently, particularly water and radiation, although the soil nutrients are not included the soils can benefit through legume N fixation ability.  The relationships between WP and RUE indicate that the links between the efficiencies in the use of radiation and rainwater remain when upgrading from CON to in-situ rainwater IRWH tillage and from solely grown crops to intercropping in a semi-arid environment. To improve WP under IRWH, several options have been proposed including increasing the HI, the proportion of transpired water, and reducing VPD. However, the effective approach to further enhance water use on a seasonal basis would be to focus on improving the capture of radiation by crops in relation to WP.

References

Reference 3, 12, 18, 20, 24, 28, 29, 41, 53 were not found in text

-Response: Reference 47 repeated: Remove the references as confused with PART-I. Remove ane edited the references and added new updated references 

Reference 49 and 51 authors and year are same; separate them by ‘a’ and ‘b’

Author Response File: Author Response.docx

Reviewer 3 Report

The presented manuscript is the second part of the two manuscripts focusing on the effect of different management practices on production, water and radiation use efficiencies in three cropping systems. This manuscript includes data mainly about water and radiation use efficiencies. The presented manuscript contains well designed experiment with many results.

However, I have some recommendations mainly for Results and Discussion section.

 

Introduction

This part is clear and sufficient.

 

Materials and Methods

You should thoroughly check all parameters and unify them throughout the whole text, tables, and figures, e.g.  parameter Yg is not defined (probably Yield used in the other manuscript?); lines 398 and 434: GY (grain yield? the same as Yg?); AGDM vs TDM (the same?); TPAR vs TIPAR vs IPAR.

At the end of the Methods, add the paragraph about statistical analyses used.

Results and Discussion

Some parts of the section Results belong to Discussion:

P7-8 L274-286; P16 L509-510, 515-517; P19 L575-584; P21 L618-626.

 

Figures

Figs. 1: there is no clear what means “Ic” and other abbreviations in legends. You should describe it in the heading.

For example, Fig 1:

“The leaf area index for maize (M) and beans (B) growing in three cropping systems (sole-M, sole-B, and intercropping – Ic) under two management practices (in-field rainwater harvesting – IRWH and conventional – CON) during the growing season for both Morago (a, c) and Paradys (b, d).”

It is necessary to correct this for the other table and figure headings.

You should also better explain statistical analyses (effect of treatment? F value and significance) used in tables and figures.

Fig. 2: I recommend to merge graphs (x axes are the same) and rainfall could be only in the bottom one.

Fig. 7: You have one red vertical line for maximum value of RUE. If you use two red (full line and dashed) a two black (full line and dashed) it will be clearer.

The unit at y-axis is probably only “g MJ-1”.

Author Response

Reviewer # 3 Response

The presented manuscript is the second part of the two manuscripts focusing on the effect of different management practices on production, water and radiation use efficiencies in three cropping systems. This manuscript includes data mainly about water and radiation use efficiencies. The presented manuscript contains well-designed experiment with many results.

However, I have some recommendations mainly for Results and Discussion section.

 

Introduction

This part is clear and sufficient.

= Added some updated references according to other reviewers 

 

Materials and Methods

You should thoroughly check all parameters and unify them throughout the whole text, tables, and figures, e.g.  parameter Yg is not defined (probably Yield used in the other manuscript?); lines 398 and 434: GY (grain yield? the same as Yg?); AGDM vs TDM (the same?); TPAR vs TIPAR vs IPAR.

• Response = GY = changed to Yg (in all cases
• AGDM use for the final total dry matter while TDM was used DM measured during the growth stages. However, all changes made to "AGDM"
• corrected as  TPAR, and changed all TIPAR to TPAR

At the end of the Methods, add the paragraph about the statistical analyses used.

• Response= Added as: 

  2.5 Statistical analysis

  Analysis of variance (ANOVA) was done for the comparison of different treatments using SAS 9.1.3 for Windows (SAS Inst Inc., 2006). When the significance of the treatment on the F-statistic is mentioned, it refers to a comparison using the least significant differences (LSD) at the 0.05 probability level. In the study, a relationship between RUE and WP was analyzed as the slope of the linear regression using aggregated data from the two locations for different cropping systems under different tillage to understand the effect of available soil water for productivity and the atmospheric demand in the semi-arid crop production system.

Results and Discussion

Some parts of the section Results belong to Discussion:

P7-8 L274-286; P16 L509-510, 515-517; P19 L575-584; P21 L618-626.

- Response - All moved to discussion section and other comments added. In general, the discussion section is re-arranged and re-write some paragrapghs

Figures

Figs. 1: there is no clear what means “Ic” and other abbreviations in legends. You should describe it in the heading.

It is explained in the cation description as commented and added legend

For example, Fig 1:= Yes = Thank you, well taken comment

“The leaf area index for maize (M) and beans (B) growing in three cropping systems (sole-M, sole-B, and intercropping – Ic) under two management practices (in-field rainwater harvesting – IRWH and conventional – CON) during the growing season for both Morago (a, c) and Paradys (b, d).”

It is necessary to correct this for the other table and figure headings.

-Response: all captions descriptions corrected accordingly 

You should also better explain statistical analyses (effect of treatment? F value and significance) used in tables and figures.

- Response: Statistical analysis section/paragraph  added 

Fig. 2: I recommend merging graphs (x axes are the same) and rainfall could be only in the bottom one.

- Response: corrected as mentioned in the comment = use only one x-axes

Fig. 7: You have one red vertical line for maximum value of RUE. If you use two red (full line and dashed) a two black (full line and dashed) it will be clearer.

The unit at y-axis is probably only “g MJ-1”. = corrected

 

Author Response File: Author Response.docx

Reviewer 4 Report

Dear authors, your manuscript addresses an interesting topic. However, major changes are needed in order to improve its structure and presentation.

 

Kind regards

Comments for author File: Comments.pdf

Author Response

Reviewer # 4 comments from the pdf file

Comment L15-16- During the typical drought season ..... deleted

Comment L17 - the main treatment changed to the main plot 

Comment Line 35 - the keywords are re-arranged and edited

Comment L38 - -45; 55-56 and other parts - The introduction section - updated with recent references  see some changes made:

Introduction- section - corrections 

The introduction section - updated with recent references added 

Improving both water use efficiency (WUE) and radiation use efficiency (RUE) in mixing cropping systems is crucial for increasing crop yields in dryland agriculture (Maitra, 2020; Pierre, 2022). The crops in an intercropping system use resources differently, complementing each other and collectively producing higher yields than when grown individually in the same area (Maitra and Gitari, 2020; Duvvada and Maitra, 2020).

Cereal-legume intercropping has several benefits, including increased yield (Yin et al., 2018), improved soil properties (Nasar et al., 2020, and increased nitrogen-fixing bacteria (Solanki et al. 2019; Yu et al., 2019). Organized intercropping systems can also make better use of resources such as light, heat, water, and nutrients, resulting in higher yields and more stable crop groups (Fan et al., 2006; Mei et al., 2012). However, to avoid negative impacts on crop growth, factors such as legume species selection, seeding rate, sowing date and row spacing must be considered to limit competition between legumes and primary crops (Lawson et al., 2007). 

Deleted section:

, in many African countries and contribute to food and nutrition security in the livelihood of smallholders. Canopy structures and root systems of cereal crops are generally different from those of legume crops.

• The last paragraph of the introduction section changed  as:

  This study, therefore, hypothesizes that maize-bean intercropping under the Improved tillage (IRWH) system increases resource productivity and efficiency compared to solely grown crops. Additionally, there are positive relationships between WP and RUE in both IRWH and CON tillage systems, with higher water deficit and lesser available radiation use in CON compared to IRWH.

  Comment L56 - added new references at the beginning of the section.

Materials and method

• Comment L92 : corrected as 'is situated at a latitude of 29^o 12’33.6”S, Longitude 26^o 50’20.3”E, and Altitude of 1516 m.....
• Comment Line 102 - Soil physical-chemical property.: Added a sentence however the details of the soils information presented in the MS - Part-I with all physical, chemical and morphological data and descriptions;- Added:The clay loam soils of the demonstration plots belong to Sapane ecotope. The basic soil morphological properties are deep dark brown and brown-grey-black, for Paradys and Morago with A horizon of clay loam having a particle size of clay 34.0% and 29.4%, respectively. 
• Comment L304-306 = the x-axis corrected and use only one at the bottom

Discussion section

• Comment: L509 510: moved to the discussion section and added information about interception and photosynthesis
• Comment L628 ---634 The Discussion section. Some parts of the result sections moved to Discussion some parts were re-write and added information and references (see the revised MS).

Conclusion section

• Comment L694--718: The conclusion section - modified and corrected and re-write the whole part and avoided the referencing: see below the new conclusion section

"Improving rainfed crop production per unit area for smallholder farmers during the short rainy season is crucial for achieving food and nutrition security. In semi-arid regions, where dry conditions (El Niño seasons) and long dry spells are common due to climate change, farmers are exploring alternative techniques to increase water productivity and use resources more efficiently. Using water harvesting techniques on marginal land can help reduce the pressure to produce grain in less productive and environmentally fragile agroecosystems. The Thaba Nchu rural community faces low productivity and needs improved techniques. However, there is poor adoption of these techniques and disorganized intercropping due to water scarcity in arid and semi-arid areas. This highlights the need for alternative techniques that increase smallholders’ productivity through the ability to capture and use resources more efficiently, particularly water and radiation, although the soil nutrients are not included the soils can benefit through legume N fixation ability.  The relationships between WP and RUE indicate that the links between the efficiencies in the use of radiation and rainwater remain when upgrading from CON to in-situ rainwater IRWH tillage and from solely grown crops to intercropping in a semi-arid environment. To improve WP under IRWH, several options have been proposed including increasing the HI, the proportion of transpired water, and reducing VPD. However, the effective approach to further enhance water use on a seasonal basis would be to focus on improving the capture of radiation by crops in relation to WP."

References:

Added and updated with recent citations in the subject matter of WUE/RUE of intercropping.... see the revised MS with yellow highlights....

Author Response File: Author Response.docx

Round 2

Reviewer 1 Report

Paper is much improved.

Reviewer 4 Report

None