I am neither farmer or knowledgeable of Uganda conditions and cultural trends.  There are many positive elements, especially if you intend to make long term efforts.  The last two surveys are somewhat repetitive, so combine into one.  If farmers do not like to share personal data, such as monthly income, try to ask questions that are helpful, but not so specific.  Such as farming in most years provides for my family needs, or I must find other work beyond farming to provide for my family, or farming is not sufficient for my family support, but I do not know how to change to other work, or improve my farm production so we can live.

If you are into ArcMap, searching for coverages on climate, topography, land use, soils, ownership boundaries, streams, rainfall and other factors might be a good tool when discussing with individual farmers, or farmer cooperatives.  If you can show them some specifics, they may be able to see for themselves how to adjust, or be more open to suggestions.  

My career was not in dry areas, but many of the concerns about extreme farming in the piedmont of SC, USA are well documented by Stanley Trimble ~1974.  There may be some papers, etc. on my researchgate that could also be of interest concerning gullies, abused lands, efforts to restore native plants, soil and water conservation practices in forestry that may have some indirect applications.  

You might add to your survey if farmers have ponds, stream diversions or wells for irrigation to augment water in dry periods, how frequently do they loose crops, if they have had soil tests for nutrients, etc., would they consider notill or low-till methods or planting legumes, etc. in off season.  Are they open to change?  Are they interested in cooperative farming or do they get other assistance when crops fail?

If you can, you might want to stratify into physiographic or climactic areas, dividing prime farm land surveys, from average and marginal lands.  Each may have its own issues.  The GIS may be very helpful in this.  If you have a farming statistics agency, perhaps their past data may be helpful.

If you are planning a short term project, I would suggest reducing to a more manageable size project, especially if implementing objectives 3 and 4 on assessing soil nutrient and moisture detail relative to production me.

 Wecliffe I have used - a while ago - a model that might help with some of your questions. See the attached, the root zone water quality management model primarily looks a agriculture and movement of Ag chemicals, including fertilizers during the growth season.

Bob

https://www.ars.usda.gov/plains-area/fort-collins-co/center-for-agricultural-resources-research/rangeland-resources-systems-research/docs/system/rzwqm/

I hope that's what we previously discussed