Tonguez
A suffusion of yellow
First to OP question
Personally I use a homebrew system where the Town itself becomes a character with its own Parameters (Ability Scores) rolled as 3d6
Authority (Cha) Political influence of the organisation/town
Economy (Con)
Culture (Wis) - Integrity of the culture and loyalty of its members/citizens
Education (Int)
Security (Str) - Military and Civil enforcement and defence
Mobility (Dex) - quickness of response and transport
A town then can acquire skills and feats and even a class template (eg Market Town, Religious Center, Military Camp etc). I've not done much with the class templates but skills and feats work, Feats in particular are used to representing new relationships (Spy Network feat giving +4 to Gather Information), technologies and particular buildings - eg the Resident Academic Feat means that the town can build a university). Other features can be added to by building new structures too (eg Irrigation suystems to raise fertility and roads to give a bonus to Mobility checks.
Towns act by using skill checks (see below)
Personally I think a yeild of 60 Bushels per 5 acres is extremely high (means a 12 bushels per acre render). In Medival England Rye had a seven-fold render and Wheat a 5-fold render so 5 acres of rye would have a yeild of 35 bushels per year, or 3-ish per month.
That being said I also don't think 5 acres is big enough if you are calculating how much land a person used to support themselves and family (as opposed the the zie of the garden plot) and would likely double (or even triple) it to take account of fishing etc
Now mechanics
Yield = Area x Render
Fertility = Arbitary number based on Soil quality, Weather, Irrigation and DM mood
Use Prof: Farmer skill check with DC = Yeild/Labour used/Fertility
so using Rye render of 7 and a 10acre feild, 1 man and his wife in good soils (Fertility 2)
Yeild = 70 (10 x 7)
DC = 70/2/2 => 17
so Prof: Farmer check vs DC 17 to achieve the desired yeild in one year
January
mending and making tools, repairing fences
showers
February
carting manure and marl
showers
March
ploughing and spreading manure
dry, no severe frosts
April
spring sowing of seeds, harrowing
showers and sunshine
May
digging ditches, first ploughing of fallow fields
showers and sunshine
June
hay making, second ploughing of fallow field, sheep-shearing
dry weather
July
hay making, sheep-shearing, weeding of crops
dry early, showers later
August
Harvesting
warm, dry weather
September
threshing, ploughing and pruning fruit trees showers
October
Last ploughing of the year
dry, no severe frosts
November
collecting acorns for pigs
showers and sunshine
December
Mending and making tools, killing animals
showers
Personally I use a homebrew system where the Town itself becomes a character with its own Parameters (Ability Scores) rolled as 3d6
Authority (Cha) Political influence of the organisation/town
Economy (Con)
Culture (Wis) - Integrity of the culture and loyalty of its members/citizens
Education (Int)
Security (Str) - Military and Civil enforcement and defence
Mobility (Dex) - quickness of response and transport
A town then can acquire skills and feats and even a class template (eg Market Town, Religious Center, Military Camp etc). I've not done much with the class templates but skills and feats work, Feats in particular are used to representing new relationships (Spy Network feat giving +4 to Gather Information), technologies and particular buildings - eg the Resident Academic Feat means that the town can build a university). Other features can be added to by building new structures too (eg Irrigation suystems to raise fertility and roads to give a bonus to Mobility checks.
Towns act by using skill checks (see below)
godawful said:5 acre farm can produce 60 bushels of food per year or, 5 bushels/month 3 required by family with 2 left over to sell or keep for seed. 1 bushel of seed is required to produce 4 bushels of food.
1 man can farm 5 acres in this way.
Personally I think a yeild of 60 Bushels per 5 acres is extremely high (means a 12 bushels per acre render). In Medival England Rye had a seven-fold render and Wheat a 5-fold render so 5 acres of rye would have a yeild of 35 bushels per year, or 3-ish per month.
That being said I also don't think 5 acres is big enough if you are calculating how much land a person used to support themselves and family (as opposed the the zie of the garden plot) and would likely double (or even triple) it to take account of fishing etc
Now mechanics
Yield = Area x Render
Fertility = Arbitary number based on Soil quality, Weather, Irrigation and DM mood

Use Prof: Farmer skill check with DC = Yeild/Labour used/Fertility
so using Rye render of 7 and a 10acre feild, 1 man and his wife in good soils (Fertility 2)
Yeild = 70 (10 x 7)
DC = 70/2/2 => 17
so Prof: Farmer check vs DC 17 to achieve the desired yeild in one year
January
mending and making tools, repairing fences
showers
February
carting manure and marl
showers
March
ploughing and spreading manure
dry, no severe frosts
April
spring sowing of seeds, harrowing
showers and sunshine
May
digging ditches, first ploughing of fallow fields
showers and sunshine
June
hay making, second ploughing of fallow field, sheep-shearing
dry weather
July
hay making, sheep-shearing, weeding of crops
dry early, showers later
August
Harvesting
warm, dry weather
September
threshing, ploughing and pruning fruit trees showers
October
Last ploughing of the year
dry, no severe frosts
November
collecting acorns for pigs
showers and sunshine
December
Mending and making tools, killing animals
showers