>> individually plucking each weed or weevil, and metering just the right amount of water for each individual plant, so that all the crops are organic.
Not even close. The sorts of critters and diseases that pesticides combat cannot be mitigated by plucking things off plants, nor can nitrogen fertilizer be replaced with elbow grease. Identifying and removing (burning) infected plants would help, but only if each plants was isolated from its neighbors, otherwise you are just back to burning fields once infection is detected. Growing each potato inside its own little box cannot scale.
For many farmers the "right amount of water" ends up being however much is available. Crop fields are not home gardens. The amounts of water needed are measured in acre-feet. Metering it out to each corn stalk individually would certainly help, but likely fails the cost/benefit analyses at scale. A corn field has roughly 50,000 plants per acre, and commercial farm several hundred acres. That will be a heck of a lot of plastic tubing to install/maintain.
Not even close. The sorts of critters and diseases that pesticides combat cannot be mitigated by plucking things off plants, nor can nitrogen fertilizer be replaced with elbow grease. Identifying and removing (burning) infected plants would help, but only if each plants was isolated from its neighbors, otherwise you are just back to burning fields once infection is detected. Growing each potato inside its own little box cannot scale.
For many farmers the "right amount of water" ends up being however much is available. Crop fields are not home gardens. The amounts of water needed are measured in acre-feet. Metering it out to each corn stalk individually would certainly help, but likely fails the cost/benefit analyses at scale. A corn field has roughly 50,000 plants per acre, and commercial farm several hundred acres. That will be a heck of a lot of plastic tubing to install/maintain.