It appeared to me that the expression was parsed wrongly and should be not avances de terre but pertes d'avance, i.e. the loss of an investment (time, money) made before the event [which I see, at the time I am posting, others are also suggesting].

"En situation d’incertitude, les agriculteurs privilégient une recherche de flexibilité. Ne sachant pas si un phénomène susceptible, par exemple, de détruire les récoltes, va se produire ou non, les producteurs tendent à minimiser les avances (monétaires ou en temps) qu’ils consacrent à la production. Dans le cas où les récoltes sont effectivement détruites, la perte d’avance sera moins grande en agissant ainsi qu’en faisant comme si l’événement redouté n’allait pas se produire, c’est-à-dire comme en univers certain : en effet en univers certain (favorable), les producteurs peuvent sans risque faire les avances exigées pour maximiser leur production dont ils savent au départ qu’elle sera certaine au moment de la récolte."
https://www.diplomatie.gouv.fr/IMG/pdf/Document_complet.pdf

I can see how this applies, as above, to the loss incurred if ground is fertilized, say, then sown, without a descent crop being harvested.

The following makes a distinction between perte d'avance en terre and perte de récolte and refers to destructions des récoltes and destruction des sols. I suppose a perte d'avance en terre corresponds to the loss of the cost of fertilizer, fuel and time in preparing the soil, while a perte de récolte would the market value of the crop at the time if could have been sold.

"En cas de prise de possession du/des TERRAIN(S) (exception faite des chemins et des plateformes d'accès aux éoliennes qui seront maintenus libres de toute culture pendant toute la durée du BAIL) en cours d'année culturale - lors d'interventions ulterieures pour les besoins de l'entretien - une indemnité pour perte d'avance en terre ou perte de récolte sera versée à l'EXPLOITANT selon les barèmes d'indemnisation des destructions des récoltes ou de destruction des sols en vigueur dans le département de lieu de situation du bien loué"

Our Canadian friends have come up with an English term for perte d'avance (en terre?:
Perte d’avance à justifier - 8 Wing Trenton
Loss of accountable advance - 8 Wing Trenton .
https://publications.gc.ca/collections/collection_2014/tpsgc... AND
https://publications.gc.ca/collections/collection_2014/tpsgc...

The term is hardly common, however, so there may well be a more 'genuine' term. But failing anything better, it does make sense.


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Note added at 7 hrs (2023-08-17 22:17:07 GMT)
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Further reading suggests that things like soil compaction (due to heavy machinery crossing land), damage to land drainage systems, possibly damage to fences, etc. might count as pertes d'avance de terre, i.e. the losses need not be seasonal as my 'fertilizer and sowing', above, suggest, but might involve any previous investment (drainage, regular ploughing, etc.) rendered useless by the windfarm works.

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Note added at 7 hrs (2023-08-17 22:25:33 GMT)
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I mistakenly included 'accountable' (Perte d’avance à justifier = 'Loss of accountable advance') in my suggestion, but I feel it actually helps in understanding the meaning.

French term (edited): avances de terres

The key elements are usually the fence or other boundary, and the use of the land. Usually, the land must be used as a part of the holding to which it is being attached, for example if a garden adjoins the land, the land encroached upon would probably need to be used as a garden too, to stand a chance of being claimed.

Boundaries and Encroachment - Naturenet


Common Land Encroachment and Works | How To Take ...
Open Spaces Society
https://www.oss.org.uk › how-to-take-action-against-u...
The owner can take action under the normal laws of trespass against a work for which permission has not been sought. Persuading the owner to take action is ...

Encroachment Definition
Investopedia
https://www.investopedia.com › ... › Home Ownership
Encroachment happens when someone traverses boundaries outlined in a survey, violating the property rights of another property owner. Encroaching on someone ...

French term (edited): perte/s d'avance(s) de terres

- suggested to me by the wording of the question as a 'section on *easements* over the land* = restrictive land covenants as (UK) local land charges or private wayleave agreements with 'statutory undertakers' (public utility companies) and as a coalescence of ideas by the gist of the Discussion Entries.

It's perte*s* d'avance*s* de terre*s* - could be encapsulated by wayleaves in the plural.