the Creative Commons Attribution 4.0 License.
the Creative Commons Attribution 4.0 License.
| 11 Jun 2026
Soil-plant-water relationships and crop yield under conservation agricultural practices: A biophysical basis for tailored adoption
Abstract. Conservation agriculture is widely promoted to reduce soil degradation, restore and maintain soil health, enhance crop productivity, and mitigate greenhouse gas emissions. This generally entails three core practices: reduced soil disturbance, permanent organic soil cover, and crop rotation. However, the universal applicability of these practices across diverse biophysical and socioeconomic contexts is under debate due to inconsistent agronomic performance and practical challenges associated with implementing all three practices simultaneously. To better understand the associated biophysical dynamic, we evaluated changes in soil-plant-water relationships and crop yields under five practices: no-till without residue (NT), reduced tillage without residue (RT), no-till with residue (NT+RR), reduced tillage with residue (RT+RR) and conventional tillage with residue retention (CT+RR), each compared with conventional tillage without residue retention (CT), using a global meta-analysis of observations from 338 studies across 361 experimental sites. Overall, yield declined by 6.1% (p = 0.024) under NT. However, yield reductions diminished with increasing tillage intensity (from NT to CT) and residue retention (p = 0.041). Sensitivity analysis revealed that yield reductions under NT are likely driven by compaction-driven adverse changes in soil hydraulic and mechanical properties limiting water movement (infiltration, redistribution and drainage), retention, and availability to crops, and root growth. Specifically, NT, irrespective of residue management, reduced soil near-saturated hydraulic conductivity – a property governing soil water replenishment, redistribution and drainage – by 26.9% (p = 0.008), increased soil penetration resistance by 29.4% (p < 0.001), and changed the pore size distribution, resulting in smaller air-capacities and larger wilting points. When reduced tillage and residue retention treatments were combined (RT+RR), yield variability was more strongly associated with changes in soil organic carbon and saturated hydraulic conductivity than water retention, and penetration resistance. Yield responses varied with local climate and soil type. NT increased yields in semi-dry climates (aridity index: 0.3-0.65) by 16.3% (p = 0.004). In contrast, NT reduced yield in humid regions (-7.2%, p < 0.001) as well as in dry regions (-8.3%, p = 0.038) where irrigated agriculture is likely to dominate. These yield responses by climate context closely mirrored the observed differences in saturated hydraulic conductivity. Yield penalties were generally greatest in clayey soils (e.g., under RT -19.3%, p = 0.047) and consistently diminished toward sandy soils, both under NT and RT. These findings highlight the need for context-specific implementation of conservation agriculture to achieve balanced agronomic and environmental benefits.
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RC1: 'Comment on egusphere-2026-2816', Anonymous Referee #1, 24 Jun 2026
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AC1: 'Reply on RC1', Mosisa Tujuba Wakjira, 12 Jul 2026
First, we would like to sincerely thank Referee 1 for the time and expertise devoted to reviewing our manuscript. We greatly appreciate the constructive feedback, insightful comments, and valuable suggestions provided. Here, we provide clarifications on these comments. Referee comments are in normal, and our responses are in italic font.
This manuscript analysis soil-plant-water relationships and crop yield under conservation agricultural practices using global meta-analysis based on observations from 338 studies across 361 experimental sites worldwide. A series soil structural and mechanical parameters of convention tillage (CT) and conservation agricultural practices (NT, NT+RR, RT, RT+RR, CT+RR) under different regions (i.e., dry, semi-dry, and humid regions) were compared. The dataset is very impressive and the analyzed hydrological and mechanic parameters have a good link with crop yield. The manuscript is well-written and the results are important for the selection of the conservation agricultural in different regions. There are some comments needs to be considered before final publication on SOIL.
We thank Referee 1 very much for the positive feedback.
As is shown in Table 2, the penetration resistance largely depends on soil moisture conditions as well as measurement procedure (field measurement v.s., lab measurement under controlled moisture), but in the manuscript how to eliminate this difference on different studies? Are all the PenR from the same water content across the 361 experiment sites? Does the author filter or standardize the soil moisture status at which the PenR was measured? If it not, the authors should explicitly discuss how this affects the sensitivity analysis (Figure 6) where PenR shows lower importance for yield.
We thank the referee for this comment. We did not standardize penetration resistance (PenR) by soil moisture because in the majority of the source literature, PenR measurements were not reported together with the corresponding moisture conditions at the time of measurement. Only a few studies provided such information (e.g., PenR measurements at field capacity), while other studies only reported the timing of the sampling (e.g., after planting, at flowering, or after harvest). For this reason, our analysis represents what we assume as an average condition. We fully agree with the referee that this is an important limitation, given the strong sensitivity of PenR to soil moisture content. In our analysis, we assume that the soil moisture states of the paired treatments (conventional tillage, CT and conservation agriculture practices, CA) at each site are comparable. Therefore, by using response ratio (CA/CT) as a relative effect size, differences in soil moisture conditions among studies are minimized because ideally, these differences cancel out within studies (at the site level). Nevertheless, there are situations where this assumption may not hold. For example, when crop performance or root systems differ strongly between treatments, the soil moisture status of the treatments may also differ because of differences in crop water uptake. As a result, if PenR measurement is carried out a relatively longer period after the last rainfall or irrigation event, the soil moisture profiles of the CA and CT treatments may differ substantially, potentially violating the assumption of comparable moisture conditions between treatments. We will clarify this in the revised manuscript, extending the discussion in Lines 485-493.
Besides, air-capacity (AC) is defined as the difference between moisture content at saturation and field capacity. However, across literature, water content at field capacity is defined differently at pF 2.0 (10 kPa) or pF 2.5 (33 kPa). The pore size boundary between 10 kPa and 33 kPa is significantly different, this boundary determines whether AC captures true aeration macropores or structural mesopores. It is recommended to clarify the proportion of studies using pF 2.0 versus pF 2.5 and whether this introduces a bias across soil textural classes (Figure 4).
We thank the referee for the valuable comment. In the majority (56%) of the studies from which moisture content at field capacity (FC) was extracted, FC was measured at pF2.5 whereas in about 19% of the studies it was measured at pF 2.0. In the remaining 25% of the studies, the suction head at which FC was measured was not reported. The dominant proportion of measurements pF 2.5 reflects the larger proportion of medium- and fine-textured soils than coarse-textured soils. This is expected as FC is determined at pF 2.0 for coarse-textured soils and closer to pF 2.5 for medium- and fine-textured soils (Hillel, 1998). While the choice of pF influences the absolute magnitude of FC and consequently AC across soil textures, it does not meaningfully affect the absolute difference in FC between NT and CT (Figure 4), as well as the response ratio of AC, as the same definition of FC was used for each individual pair of control (conventional tillage, CT) and treatment (no-till, NT). We will clarify this point in the revised manuscript where appropriate.
In the discussion, Figures 7 and Figure 8 show new information about global correlation matrix and comprehensive pedoclimatic grid cross-referencing 12 soil properties with crop yields. However, the discussion part should be ideally reserved for mechanic interpretation, literature comparison, etc, rather than introducing new complex statistical analysis. Therefore, it’s recommended to create a new subsection in results part and put figure 7and 8 into this part, and this would make discussion more logical and coherent for readers.
Thank you very much for this constructive comment; we will implement this in the revision.
Line 55: …plant CO2 uptake; Line 90: all reporting 90 overall yield reductions under no-till when it is adopted alone; Line 116: delete the repeated sentence “for identifying the conditions in which CA”; Figure 8: check the spelling error “Robust positive” in the legend.
Thank you. We will correct them in the revised manuscript.
Table Formatting: For Tables 1 and 2, please reform them into the standard three-line table format as required by the SOIL journal guidelines. Remove all vertical lines and keep only three primary horizontal lines (top, bottom, and header line).
Thank you. We will revise the table as per the guidelines of the journal.
References:
Hillel, D.: Environmental Soil Physics, Toronto, 801 pp., 1998.
Citation: https://doi.org/10.5194/egusphere-2026-2816-AC1
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AC1: 'Reply on RC1', Mosisa Tujuba Wakjira, 12 Jul 2026
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RC2: 'Comment on egusphere-2026-2816', Anonymous Referee #2, 10 Sep 2026
This paper explores various relationships between conservation agriculture practices and important soil-plant-water parameters. The statistical tests done were really impressive, reflecting the objectiveness of the researchers. This paper is really relevant in practice and a lot of stakeholders in the agricultural sector would benefit from this. Well done!
I can say that this paper can be accepted, subject to minor revisions. I have some suggestions to help improve the content (motivation, presentability and readability of findings, outlook):
Line 55 - "CO2" --> CO2
Line 60 - what hinders the implementation of conservation agriculture as a "package"? Maybe describe in 1-2 sentences.
Line 77 - "reasons" --> "reason" (should be singular?)
Line 124 - Maybe you can elaborate more how exactly you selected these parameters? Was there a system/classification you used to select these? Because technically, soil texture/grain size is also a "soil parameter" that can regulate soil-plant-water relationships as well, but is not explicitly selected for Table 2 (albeit you classified your findings according to soil textures in your Results section).
Line 146 - remove space in "c an" --> "can"
Line 257 - which preliminary tests did you perform to test for potential interaction effects? Briefly mention these tests
Line 337/Figure 3 - I think you can minimize the details presented to enhance readability
1) I would also suggest that you present this figure in the main text without the numbers in brackets and also the light blue fills (I do not think it contributes much to the key message). Maybe the red circles can be changed to an arrow oriented along the significant trend along gradients.
2) Then transfer this current detailed figure with the numbers in bracket in the appendix/supplementary material. Also, are the blanks there (e.g., DRY under RT+RR) because there are 0 studies? Maybe report this as [0, 0] in the figure (that you transfer later on to the supplementary material, if you agree).
3) Maybe reduce the abbreviations to help enhance readability e.g., would it be possible to spell out "Semi-Dry" and "Humid"? And Aridity Index instead of AI? Just retain the abbreviations for the conservation agriculture practices and Ks
Figure 2 - same as Figure 3, please consider removing the light blue fills and the numbers? And transfer this current figure you have to the appendix/supplementary material?Line 374/Figure 4 -
1) When you said "were compiled using observations reported across studies", did you mean you averaged these values? Maybe be clearer on what you mean by compiled.
2) Do the purple fills really matter here as well? Can't you just present Figure 4 without the purple fill and put the current version of the figure (With the purple fills) in the appendix instead? It is a good practice that you are thoroughly transparent with your reporting of findings, but I am not sure how much these filled points add value to the message in the main paper.Line 398/Figure 5: same as Figure 3 and 4
Line 471/Figure 7: In the correlation heatmap, maybe change purple shades to red shades to make the negative feeling stand out
Line 512: "findings Blanchy et al." --> findings of Blanchy et al."
Line 529 and other lines mentioning "water stress": please change to "drought stress" (I think you are referring to this one). Water stress could be vague, which could mean either drought stress or wet/waterlogging/anaerobic stress
Figure 8: To make it easier to read, maybe put the subplot headings already. For example: "(a) Across climates"; "(b) Across soil textures", "(c) Across durations of conservation practices. Then remove those captions. And I do not really see the added value of changing shapes for crop yields if the square is just on 1 major column "Yield". I think you can minimize such detailed differences to make the figure easier to read.
And since light green and light pink might not be good for color blinded people. Maybe change the green to blue. And change the yellow --> white
Line 603: "Achankeng and Cornelis, (2023)" --> "Achankeng and Cornelis (2023)"
Other things
1) Maybe mention at the end of the paper (limitations? conclusions?) that more scientific studies on conservation agriculture might be needed on underrepresented regions shown in Fig. 1 map. And mention some examples of these underrepresented regions where conservation agriculture is still relevant e.g., Southeast Asia? Central America?2) To enhance readability, maybe remove the p-values in the main text and transfer them to appendix/supplementary material (perhaps in a table along with the described finding that was tested )
Citation: https://doi.org/10.5194/egusphere-2026-2816-RC2 -
AC2: 'Reply on RC2', Mosisa Tujuba Wakjira, 15 Sep 2026
Referee comments are in normal, and author responses are in italic font.
This paper explores various relationships between conservation agriculture practices and important soil-plant-water parameters. The statistical tests done were really impressive, reflecting the objectiveness of the researchers. This paper is really relevant in practice and a lot of stakeholders in the agricultural sector would benefit from this. Well done!
I can say that this paper can be accepted, subject to minor revisions. I have some suggestions to help improve the content (motivation, presentability and readability of findings, outlook).We thank Referee 2 very much for the time and expertise devoted to reviewing our work, and we greatly appreciate the detailed review, positive assessment, and constructive suggestions for further improvement of the manuscript. We will incorporate the corrections and carefully consider the suggestions in revision.
Line 124 - Maybe you can elaborate more how exactly you selected these parameters? Was there a system/classification you used to select these? Because technically, soil texture/grain size is also a "soil parameter" that can regulate soil-plant-water relationships as well, but is not explicitly selected for Table 2 (albeit you classified your findings according to soil textures in your Results section).
We thank Referee 2 for the suggestion and question.
The selection of the soil parameters was based on their mechanistic effects on soil hydraulic functions, i.e., soil water flow (saturated and near-saturated hydraulic conductivity), soil water retention and aeration (plant-available water capacity, wilting point, and air-capacity), and on root growth (penetration resistance) as described in Lines 103-107. The referee is correct that soil texture is an important parameter regulating soil-plant-water relationships. Our selection, however, targets soil properties that are relatively dynamic and are influenced by soil management practices such as CA. In contrast, soil texture is a relatively static inherent property and is not directly responsive to changes in soil management. Small changes in measured soil texture can, however, be expected under deep tillage operations that mix soil from different soil layers that may differ in their textural composition. Furthermore, erosion can lead to a preferential loss of clay particles or expose deeper soil layers with a different texture. We will clarify these points in the revised manuscript.Line 257 - which preliminary tests did you perform to test for potential interaction effects? Briefly mention these tests
Thank you.
The preliminary analyses testing for possible interaction effects among moderators on the responses of soil parameters and yield to adoption of the CA practices were also based on meta-regression with interactive terms using the metafor package in R, and the test statistics was based on the default Wald-type Z-test. We will clarify this in the revision.Line 337/Figure 3 (and also 2, 4, and 5)- I think you can minimize the details presented to enhance readability.
We thank the referee for emphasizing the readability of the manuscript and appreciate the suggestion to simplify the figures. We will carefully consider this recommendation. However, given that the universal applicability of the system is highly debated: on the one hand, there is empirical evidence for an imbalance between the anticipated agronomic outcomes and environmental benefits, and many argue that the adoption of the system should be targeted to suitable contexts; on the other hand, it is widely promoted by many stakeholders, including researchers, and supported by policymakers as well as development organizations. With our analysis, we try to present evidence that may help sustainable adoption. Therefore, we place value on transparently presenting the statistical evidence supporting our findings. Our team of authors come from diverse disciplines, including soil science, soil physics, hydrology, systems agronomy and applied statistics, and recognize that different users/readers of these findings may place different levels of emphasis on statistical evidence and effect estimates. We therefore believe that retaining the sample sizes shown in brackets and the statistical significance indicated by the light blue fills provides useful information for readers who wish to assess the strength and robustness of the reported findings, while leaving the interpretation of the results to the reader. Regarding the blank cells, these indicate that the corresponding category contained fewer than five studies, and does not always mean [0,0]. We hope that the referee will find this rationale acceptable.
Line 60 - what hinders the implementation of conservation agriculture as a "package"? Maybe describe in 1-2 sentences.
Thanks for this question and suggestion.
The implementation of CA as a complete package can be constrained by biophysical, socioeconomic, and technical barriers (Giller et al., 2009; Heller et al., 2024). Biophysical constraints include, for example, increased risks of waterlogging in humid environments with fine-textured soils and greater weed and pest pressure under reduced soil disturbance, while socioeconomic and technical constraints include limited availability and competing uses of residues (particularly in smallholder farming system context), insufficient access to appropriate machinery (especially in high-input farming systems) and inputs, and inadequate policies or incentives to offset potential short-term agronomic trade-offs. We will briefly describe this in the revision.Figure 8: To make it easier to read, maybe put the subplot headings already. For example: "(a) Across climates"; "(b) Across soil textures", "(c) Across durations of conservation practices. Then remove those captions. And I do not really see the added value of changing shapes for crop yields if the square is just on 1 major column "Yield". I think you can minimize such detailed differences to make the figure easier to read.
Thanks. We will consider this accordingly. Regarding the shapes used in the figure, the use of circles for the soil parameters and squares for yield was aimed to handle the different interpretations of these changes in variables: Changes in soil parameters were interpreted relative to their implication for yield, i.e., the effect is considered positive if it favours crop yield and vice versa. Using the two different shapes, we aimed to represent the changes in the parameters as the potential drivers of the changes in yield (response).
Once again, we thank the referee for the thoughtful and constructive comments and suggestions. We hope that we have clarified the main points raised by the referee. We will carefully consider and incorporate the suggestions as appropriate and provide a detailed, point-by-point response to all of the referee’s comments in the final response.
References:
Giller, K. E., Witter, E., Corbeels, M., and Tittonell, P.: Conservation agriculture and smallholder farming in Africa: The heretics’ view, https://doi.org/10.1016/j.fcr.2009.06.017, 1 October 2009.
Heller, O., Di Bene, C., Nino, P., Huyghebaert, B., Arlauskienė, A., Castanheira, N. L., Higgins, S., Horel, A., Kir, A., Kizeková, M., Lacoste, M., Munkholm, L. J., O’Sullivan, L., Radzikowski, P., Rodríguez-Cruz, M. S., Sandén, T., Šarūnaitė, L., Seidel, F., Spiegel, H., Stalenga, J., Uusi-Kämppä, J., Vervuurt, W., Keller, T., and Vanwindekens, F.: Towards enhanced adoption of soil-improving management practices in Europe, Eur. J. Soil Sci., 75, 1–17, https://doi.org/10.1111/ejss.13483, 2024.Citation: https://doi.org/10.5194/egusphere-2026-2816-AC2
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AC2: 'Reply on RC2', Mosisa Tujuba Wakjira, 15 Sep 2026
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This manuscript analysis soil-plant-water relationships and crop yield under conservation agricultural practices using global meta-analysis based on observations from 338 studies across 361 experimental sites worldwide. A series soil structural and mechanical parameters of convention tillage (CT) and conservation agricultural practices (NT, NT+RR, RT, RT+RR, CT+RR) under different regions (i.e., dry, semi-dry, and humid regions) were compared. The dataset is very impressive and the analyzed hydrological and mechanic parameters have a good link with crop yield. The manuscript is well-written and the results are important for the selection of the conservation agricultural in different regions. There are some comments needs to be considered before final publication on SOIL.
As is shown in Table 2, the penetration resistance largely depends on soil moisture conditions as well as measurement procedure (field measurement v.s., lab measurement under controlled moisture), but in the manuscript how to eliminate this difference on different studies? Are all the PenR from the same water content across the 361 experiment sites? Does the author filter or standardize the soil moisture status at which the PenR was measured? If it not, the authors should explicitly discuss how this affects the sensitivity analysis (Figure 6) where PenR shows lower importance for yield.
Besides, air-capacity (AC) is defined as the difference between moisture content at saturation and field capacity. However, across literature, water content at field capacity is defined differently at pF 2.0 (10 kPa) or pF 2.5 (33 kPa). The pore size boundary between 10 kPa and 33 kPa is significantly different, this boundary determines whether AC captures true aeration macropores or structural mesopores. It is recommended to clarify the proportion of studies using pF 2.0 versus pF 2.5 and whether this introduces a bias across soil textural classes (Figure 4).
In the discussion, Figures 7 and Figure 8 show new information about global correlation matrix and comprehensive pedoclimatic grid cross-referencing 12 soil properties with crop yields. However, the discussion part should be ideally reserved for mechanic interpretation, literature comparison, etc, rather than introducing new complex statistical analysis. Therefore, it’s recommended to create a new subsection in results part and put figure 7and 8 into this part, and this would make discussion more logical and coherent for readers.
Line 55: …plant CO2 uptake
Line 90: all reporting 90 overall yield reductions under no-till when it is adopted alone
Line 116: delete the repeated sentence “for identifying the conditions in which CA”
Table Formatting: For Tables 1 and 2, please reform them into the standard three-line table format as required by the SOIL journal guidelines. Remove all vertical lines and keep only three primary horizontal lines (top, bottom, and header line).
Figure 8: check the spelling error “Robust positive” in the legend.