I have a 15 HP motor which pumps water from a well/reservoir to my farm. The distance is 3 kms and the required head is 67 m. Initially, we were using a tractor and a mechanical pump to achieve this before we got an electrical connection. The tractor was 50+ HP. So this capacity requirement sounds about right!
In my opinion, using diesel for irrigation will quickly bring a person/farmer to his knees (especially the capacity that your are pointing to). Fuel consumption at full load will be around 5 to 6 liters. I remember spending upwards of 20000 INR solely for the purpose of filling up my farm pond. Makes no sense to pursue drip irrigation on diesel power.
Having said this, you can look at folks who convert old TATA 407 engines into generator packs. You can always ask for specific generators. I prefer Mecc Alte generators as they are very efficient. But you need to check the service and support in your area. These generator packs are wheel mounted and can be lugged around with the help of tractors. They make a lot of sound as they are not sound proofed.
You can get the covered ones which hardly make any sound but they might double your capex. But you can rent them out for functions, capital works etc. By law, the aforementioned ones cannot be used in public places.
Have you tried speaking to your fellow farmers and find out if you can share electricity with them? Maybe few of you can come together for buying one generator. If you can be specific around your need, maybe you may have other suggestions rolling in.