the Creative Commons Attribution 4.0 License.
the Creative Commons Attribution 4.0 License.
Evaluation of a long-term optimized management strategy for the improvement of cultivated soils in rainfed cereal cropland based on water retention curves
- 1Institute for Innovation & Sustainable Development in Food Chain (IS-FOOD), Universidad Pública de Navarra (UPNA), Campus de Arrosadia, 31006 Pamplona, Spain
- 2Department of Engineering, Ed. Los Olivos, Universidad Pública de Navarra (UPNA), Campus de Arrosadia, 31006 Pamplona, Spain
- 3Department of Science, Ed. Los Olivos, Universidad Pública de Navarra (UPNA), Campus de Arrosadia, 31006 Pamplona, Spain
- 4Department of Agricultural Engineering, Biotechnology and Food, Ed. Los Olivos, Universidad Pública de Navarra (UPNA), Campus de Arrosadia, 31006 Pamplona, Spain
- 1Institute for Innovation & Sustainable Development in Food Chain (IS-FOOD), Universidad Pública de Navarra (UPNA), Campus de Arrosadia, 31006 Pamplona, Spain
- 2Department of Engineering, Ed. Los Olivos, Universidad Pública de Navarra (UPNA), Campus de Arrosadia, 31006 Pamplona, Spain
- 3Department of Science, Ed. Los Olivos, Universidad Pública de Navarra (UPNA), Campus de Arrosadia, 31006 Pamplona, Spain
- 4Department of Agricultural Engineering, Biotechnology and Food, Ed. Los Olivos, Universidad Pública de Navarra (UPNA), Campus de Arrosadia, 31006 Pamplona, Spain
Abstract. This study evaluates an optimized cropping system (including no-tillage, cover crops and organic amendments), as an alternative to conventional management for rainfed cereal cropping in a calcareous soil in a semi-arid Mediterranean climate zone in Navarre (Spain), based on the analysis of soil water retention curves (SWRC) and soil structure. In an agricultural area, plots were randomly selected on a soil unit (Fluventic Haploxerept), with contrasting managements: (a) optimized system; which includes no-tillage (18 years continuous) after conventional tillage, crop rotation, use of cover crops and occasional application of organic amendments, and (b) conventional management; which involves continuous conventional tillage (chisel plow), mineral fertilization, no cover crops and a lower diversity of crops in the rotation. Undisturbed soil samples from the soil surface (0–5 cm) and disturbed samples from the tilled layer (0–30 cm) were collected for both systems. The undisturbed samples were used to obtain the detalied SWRCs in the suction range 0 kPa to 110 kPa using a Hyprop® device. From these SWRCs, the Dexter S index was determined. Disturbed samples were used in the laboratory to assess soil structure by means of an aggregate-size fractionation. SWRCs showed significant differences between the two studied agricultural systems, corresponding to different pore size distributions. However, the S index did not show significant differences between the two cropping systems. In addition, the soil under conventional management showed greater macroporosity (gravitational water). As a result, the soil under the optimized system stored up to 10 % more water for the crop at the studied depth. Likewise, more stable macroaggregates were observed in the optimized system than in the conventional one, as well as more organic C storage, greater microbial activity, and biomass. Overall, these results reflect a better quality –or less degradation– of the soil after 18 years under the optimized system than its conventionally managed counterpart.
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Alaitz Aldaz-Lusarreta et al.
Status: open (until 12 Jun 2022)
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RC1: 'Review SOIL: egusphere-2022-131', Johan Bouma, 04 May 2022
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This reviewer strongly supports the type of research that the authors present in their paper: characterize field conditions on soils where certain management types have been applied for a substantial period. The authors also present a professional paper in terms of methods used, particularly the method to measure retention curves ,and by applying multiple experiments and proper statistical analyses.Unfortunately, when they conclude in the end that: “the study contributes to higher sustainability of mediterranean agrosystems”, they are off the mark. Sustainable development is defined as having economic, social and environmental dimensions as expressed by the UN Sustainable development Goals (SDG) and the associated European Green Deal. Scientific papers published in 2022 that suggest a link with sustainable development cannot ignore these developments in the scientific, policy and public arena’s. The title of the paper is also highly misleading: “improvement of cultivated soil” cannot be based only on: “water retention curves”. Numerous published papers describe a systems analysis based on the interaction between soils-water-atmosphere-plants that is needed to assess effects of soil management.
Sustainable development implies for agriculture at least: production of healthy food ( SDG2&3), protection of ground- and surfacewater quality (SDG6), carbon capture and reduction of greenhouse-gas emission (SDG13) and increasing biodiversity and combatting land degradation (SDG 15).
I would recommend that the authors frame their results in a SDG context:
1. It should not be too difficult to report crop yields. (SDG2&3)
2. Water tables may be deep and not polluted; this could be mentioned showing that groundwater quality is not really an issue here.(SDG6)
3. Carbon capture is not evident as the %C is about the same for OPM and CM. This is interesting because OPM management is supposed to lead to higher %C and their results indicate this may apply to soils in humid regions ,as reported in literature, but not in arid climates. Effect of high temperatures? But.. data only are restricted to 30 cm depth. (SDG13)
4. Even though the carbon content of both treatments is about the same, the biological soil properties seem to differ. Biodiversity in OPM is higher. This result is interesting because information on soil biology is often missing in other publications and could be part of the main text here and not be presented in an appendix. (SDG15)
5. As bulk densities of the two treatments are about the same for 0-5 cm dept and for the 0-30 cm depth( how was the latter measured, we read only the method for 0-5 cm? Effect of high tempera) there seems to be no negative effect on soil structure by CM management which is usually assumed to take place. Big problem here is that analyses were only made to 30 cm depth and a plowpan may well form by CM management but usually occurs at 30 cm depth and deeper. Indeed, as the authors mention on line 320: deeper soil layers are needed. For a correct analysis soils should be analysed for the total rooting depth. (SDG15).Some additional notes:
1. Line 45: to study soil pores, morphological analyses are most useful, if only because different types of macropores can be distinguished: e.g. channels of roots or animals or cracks . Deriving pore sizes form moisture retention data is an indirect, approximate method. Later ( lines 260, 266) micromorphology is mentioned. That should also be done upfront.
2. Line 190: no significant compaction? Could be deeper in the CM soil, see comment above.
3. Line 319: infiltration at the surface is mentioned in the context of the pore analysis. But infiltration rates can be measured and this is very important for the Mediterranean environment , certainly when considering climate change where showers will become more intense. CM has more macropores, so the authors suggest that infiltration rates would be higher than in OPM with fewer macropores. But the CM soil is less stable so crusts may form rapidly, the more so since there are no cover crops and crop residues are removed. So just linking the occurrence of physically derived macropores to infiltration rates is unrealistic without measurements of such rates. In fact, the reasoning should be reversed: measure infiltration rates and then explain differences by looking at pore patterns.
4. The authors conclude that more water is stored in the OPM treatment and this should be favorable for plant growth. But this is a statement based on static moisture retention measurements while storage is determined by in- and outflow from a certain soil volume, a dynamic process as is the moisture supply to plants. Numerous dynamic simulation models are available to quantify this process, that needs hydraulic conductivities of the soil. The authors seem to be unaware of modern soil physical theory.
5. As the soil index by Dexter does not provide any valuable results ( lines 226, 317) it should receive much less attention and might as well be omitted.A possible new title might be: Effects of innovative soil management on topsoil properties of a Mediterrenean soil. This could focus on several interesting results identified above. Again, I would recommend they would frame their story in an SDG context.
The authors should realize that OPM is, in fact, a form of regenerative agriculture, studied in the USA. I recommend that they check with the National Soil Health Institute website. info@soilhealthinstitute.org.
J.Bouma.
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EC1: 'Reply on RC1', Simeon Materechera, 15 May 2022
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I agree with the observations of this reviewer and will awiat responses and comments from the authors
EC
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EC1: 'Reply on RC1', Simeon Materechera, 15 May 2022
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RC2: 'Comment on egusphere-2022-131', Anonymous Referee #2, 13 May 2022
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General comments:
The purpose of the manuscript is a simple comparison of the influence of two management systems, conventional cropping and direct-drilling rain-fed cropping in the physical properties of a soil in the north of the Spain. The selected physical properties are the S index of Dexter (2004) and the size distribution of the stable aggregates. Neither the objectives nor the methods represent a new contribution to the fields of Agronomy or Soil Science.
Nevertheless, the relevance of reduced tillage systems for the Mediterranean countries, and the long duration of the field trials, deserve an opportunity for the authors after a thorough revision of the manuscript. Some recent contributions as, for instance, Or et al. (2021) could be inspiring for such a revision.
The Introduction section does not contain a comprehensive, updated perspective of the conservation agriculture and the quality of the soil. Consequently, the objectives, (lines 77-82) are very imprecise.
The Material and methods section is rather incomplete, with some inaccuracies that will be commented later. The climate properties of the study zone are missing. The description of the soil is limited the mention of the subgroup in the Soil Taxonomy scheme, the textural class of the upper soil horizon and Tables 1 and A1. No explanation is given in the text of the methods followed for the determination of the data of Table1. However, the details of the soil water retention in subsection 2.2 and of the aggregate size fractionation in subsection 2.4 are excessive including Figure 1.
The Results and discussion section is incomplete as well. The authors have chosen the van Genuchten soil water retention equation, but, in addition to the absence of the fitted values of its parameters in the text, one misses some consideration of other alternatives as, for instance, the multimodal equations, which according to Jensen et al. (2019), can reflect better the effects of management systems in the soil properties. I have expected some changes in properties like the bulk density, and the presence of some surface crusts, but, apparently, they were not found. The Figure 3 could not give an adequate information on the size distribution of the pores since it is estimated from the soil water retention curve through equation (2). The discussion of the results is fragmentary.
Specific comments
Line 18: instead of ‘unit’ it must be written subgroup.
Lines 25 and 26: ‘significant differences’ must be replaced by a statistic parameter.
Line 28: what is ‘the studied depth’?
Lines 33-38: The paragraph should be rewritten to improve its comprehension.
Lines 45-47: The sentence is very similar to that of the lines 37-38.
Lines 51-53: The definition of the soil water retention is very imprecise. Why soil water retention ‘is mainly associated with the porous system’ ‘at low suctions’?
Line 56: The treatment of the air entry state is, again, imprecise. The term ‘so-called’ is unnecessary.
Lines 67-70: This paragraph is unclear.
Lines 71 and 77: The two sentences are almost repeated.
Line 85: for the sake of precision write ‘subgroup’ instead ‘type’ and mention the Soil Taxonomy.
Line 86: The textural class should be silt loam, according to the particle size information of Table A1, where it was correctly indicated.
Lines 88-90: A more complete description of the soils should have been very helpful to understand their behavior. One cannot trust ‘the visual inspection’ to affirm that the soil is homogeneous. As in the line 28, could ‘the study depth’ be defined?
Line 105: The term ‘coverer’ is very odd.
Table 1: The evaluation method must be indicated in the text and the relevant details like the soil-water ratio for the suspension in the measurement of the pH and of the electrical conductivity.
Line 129: Use ‘matric component of soil water potential’ instead of ‘hydric potential’ to be more precise.
Lines 132-133: To establish the relationship between the gravimetric and volumetric water contents, one only need to know the bulk density of the soil. The sentence is confusing.
Lines 142-145: I could not find equation (1) in the article of Dexter (2004a). In fact, I cannot find the relation of this equation with the van Genuchten (1980) equation.
Lines 150-154: The equation was not proposed by Jurin (1718) as one can check reading such an article. Jurin described his observations in that contribution, but the equation was later formulated by Young and Laplace. This equation is usually known as the Young-Laplace equation (e.g. Adamson, 1967, § I.10).
Line 154: Is the (soil water) potential is mentioned, the sign should be negative. The term ‘suction’ is more appropriated here if the symbol ‘h’ has been used for the ‘height’ in the line 152.
Line 195: The term ‘water capacity’ was already defined, at least, by Arnold Klute in 1952.
Line 196: How ‘field capacity’ is defined in the text? This term must be precisely defined.
Table 2: as indicated above the soil water potential is negative.
Lines 231-233: If the authors are using a structural index, they should not compare the texture but the structure of the soil.
Line 306: The term ‘capillary/available water’ is misleading.
Line 322: I do not think that tillage should be ‘suppressed’. The natural consolidation of the soil surface might be alleviated by occasional shallow tillage operations.
Technical corrections:
Line 54: Writing ‘saturated’ soil is enough.
Lines 146-147: The use of the acronym ‘SUHC’ is needless.
Lines 160 and 364: The correct name is Elliott.
Line 280: The Table reference is A1, not ‘S1’.
Line 235 and caption of Figure 3: The proper adjective is logarithmic.
Incomplete references: Lines 366, 369-370, 373-374, 381, 387-388, 391, 407, 419.
The reference of lines 441-442 is not mentioned in the text.
References:
Adamson, A.W. 1967. Physical chemistry of surfaces. 2nd ed. Wiley-Interscience. New York.
Jensen, J.L., Schønning, P., Watts, C.W., Christensen, B.T., Munkholm, L.J. 2019. Soil water retention: Uni-modal models of pore-size distributions neglect impact of soil management. Soil Sci. Soc. Am. J. 83: 18-26.
Klute, A. 1952. A numerical method for solving the flow equation for water in unsaturated materials. Soil Sci. 73: 105-116.
Or, D., Keller, T., Schlesinger, W.H. 2021. Natural and managed soil structure: On the fragile scaffolding for soil functioning. Soil Till. Res. 208, 104912.
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EC2: 'Reply on RC2', Simeon Materechera, 15 May 2022
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Both the general and specific comments by the reviewer are pertinent and require a detailed response from/by the authors
EC
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EC2: 'Reply on RC2', Simeon Materechera, 15 May 2022
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RC3: 'Comment on egusphere-2022-131', Anonymous Referee #3, 17 May 2022
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The authors aiming for comparison of different regenerative soil management systems in comparison to conventional managed systems. They use various measures of soil structure and water retention to evaluate the quality of the management options. The topic is highly relevant for the adoption of cropping systems to climate change.
Unfortunately, the quality of the study does not convince me to suggest a publication in SOIL. The study is very weak in terms of field replications and study sites that leading in total to 6 samples. The analytical tools are basic and provide no innovative approaches. For such a small sample set one could expect much deeper analytical afford. Method descriptions partially missing and some data I found by luck in the supplements. In the cause of the review process I stopped marking down all individual specific comments. There was simply too much to correct and my time is limited.
General comments
The introduction should summarize the state of the art and introduce to the relevance of the topic. Unfortunately a larger part of the introduction (L51-70) contained technical information and methodological information. I recommend to go deeper into literature on soil management options of arable land and the connection between management of soil structure and water budget.
The study site is not characterized well. Climate data are missing at all and the distance between the two study sites is unclear. A map would help. No information on the type of management (experimental field trial or on farm research) is provided. Since this are calcareous soils, information about parent material would be helpful. How deep below soil surface starts the bedrock? Soil texture should be measured in replicates. The method must be described. Please show the data in the main manuscript from each sample. There must be a prove (correlation etc.) that there are no texture based differences on soil properties such as soil OC or CEC. It is recommended to show values from deeper soil layers (>30cm). Otherwise the effect of texture should be evaluated. There are also several uncertainties on fertilizer management: What form of OM amendments, how much, when in the crop rotation? What kind of cover crops? Please provided more details to the sampling design: Size of the fields, distance between the sampling points in a map.
Unsing an ANOVA approach for statistic comparison requires the assumption of normality. Further, the sample size of 3 is very low and likely not the suitable measure. I recommend using a simple T-test, depending on the distribution of the data.
The data set on microbial parameters should be incorporated in the main manuscript. Methods must descried properly. The same is true for the OC measurements. Have the carbonates be removed from the samples?
In the conclusion there something written with vegetable cover, that was not discussed before. I did not get this point. The author’s proclaimed the “optimized management” practices for the whole Mediterranean region. From this very limited data set at one sampling site it is not possible to scale up the management tools across the whole Mediterranean environment. Also the effects in the subsoil have not been taken into account.
I also highly recommend a professional language check. Many basic rules for preparing a scientific publication are ignored. For example: The manuscript is overloaded with double brackets, grammar errors or punctuation errors. Many paragraphs are not accessible, even after reading several times.
Specific comments:
L39 change eliminate to avoid. Further, cover cropping have nothing to do with soil tillage practices, examples for reduced soil tillage are e.g. mini tillage (0-10cm) , Cultivator application and everything that avoids to invert the soil of 0-30cm.
L 43 the annual soil water balance primarily depend on precipitation: I suggest optimisation of the infiltration and water storing capacity
L51-70 this belongs to the materials &method section. If you write a paper on the methods you could bring this here.
L78 managed
L86-88 the sentence is overloaded with brackets. Avoid double brackets and remove some them. Keep this in mind for the rest of the manuscript.
L97-102 this is unclear. Is only the cereal straw removed from the fields? I never heard that straw of legumes and rapeseed is removed?
L 107 which form of OM amendments, how much nutrients and OC therein?
L245 - following. Use space between ± and the number. The same is true for >. Only between the numbers an % there should not be a space.
L235-238 no consistency Fig. Figure. The two paragraphs double.
L246 texture homogeneity was not measured.
L311 where does the vegetable cover comes from ?
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EC3: 'Reply on RC3', Simeon Materechera, 17 May 2022
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Comments greatly appreciated and thank you.
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EC3: 'Reply on RC3', Simeon Materechera, 17 May 2022
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Alaitz Aldaz-Lusarreta et al.
Alaitz Aldaz-Lusarreta et al.
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