Comment on soil-2021-17

This is an important and timely study that fits well into the SOIL journal. The authors do not provide sufficient details on the methods to provide a full judgement on the validity of their results, but my overall impression is that their conclusions are well supported by the data. The manuscript is written in technically correct English, but I think that some sections need to be substancially improved before publication (see below). I therefore think that the authors should be given the chance to substnacially improve the manuscript before publication (major revision or rejection with invitation to resubmit).

This is an important and timely study that fits well into the SOIL journal. The authors do not provide sufficient details on the methods to provide a full judgement on the validity of their results, but my overall impression is that their conclusions are well supported by the data. The manuscript is written in technically correct English, but I think that some sections need to be substancially improved before publication (see below). I therefore think that the authors should be given the chance to substnacially improve the manuscript before publication (major revision or rejection with invitation to resubmit).
Specifically, I think that the quality of the different section of the manuscript varies a lot. In my opinion, the results and discussion sections are well developed and can be published with little modification, whereas introduction and methods sections need substancial improvement. The introduction is very short and does not provide a full overview about what is known about crop-to-vegetable transition impacts on soils. The text also misses 'flow' from one paragraph to the next. I would recommend to broaden the introductino, and look at crop-to-vegetable-transitions studies conducted throughout various climate systems. In addition, the introduction could explain how the different parameters measured are affected by this transition, and what results are therefore expected. In the methods section, a lot more detail needs to be provided with regards to data sources and analytical methods.
I have one major scientific concern that should be addressed by the authors. The manuscript states that soil properties of fields converted to vegetable farming were similar to those retained in conventional crop rotation. I think this authors need to provide more evidence for this point as it is an essential condition for the validity of their findings. In particular, I am wondering if the authors have any information whether the fields that were transitioned from conventional to vegetable farming were chosen randomly, of if farmers took soil properties into consideration when deciding if a given field was converted or not. If the latter were the case, the initial conditions of these field would be different from those retained in traditional crop rotation, which would limit the authors ability to link difference in soil properties to farming practices. This also applies to effects of timesince-conversion, since the farmer's considerations could change over time.
Minor comments: L37: per unit nutrient inputs: Specify which unit you refer to (area?) L64-70: the data presented here should be supported by references. L81: farmers' survey methodology: I assume this refers to an established survey or similar undertaking, but this is likely lost in the translation, and comes across quite confusingly. I recommend clarifying this. Section 2.3: A lot more detail is needed here. Ideally, a reference should be provided for each method, along with enough details such that the reader can reproduce the measurements.
Section 2.4: Here as well more detail needs to be provided. What were the nutrient concentration in each fertilizer, and how were they obtained (source?).
Section 2.5: The use of a two-segment fitted line in Fig 2b is inappropriate because there are only 3 independent datapoints (underlying replicates are not independent of each other). Essentially, this just connects two points with a line in between. I also don't think this contributes to the findings of the paper, so I would recomment removing it. Also, provide an overview on the amount if each fertilizer used in each treatment group.    Data availability: Raw data should be placed in a publically available repository to meet the Copernicus/EGU data policy.