Please,Could anyone suggest me an ON-CAMPUS 1 YEAR MBA Agribusiness in United States?

Why not use the search on this site?
https://find-mba.com/search/result?area=15&specs=57

In general, there aren't many one-year MBA options in the States; the accepted format is usually two years. So you only have a couple of options for such a specific need: if you have indeed used the search function on this site, as Alain suggested, you'd see that you're pretty much limited to Cal Poly San Luis and South Carolina State University. Of those, the Cal Poly program is the only accredited program.

Why not look for something more robust? UC Davis would be an optimal choice: it's fully accredited, in California's Central Valley, one of the most productive agricultural centers in the world, and has some good MBA options in agriculture and agribusiness. It's a two-year program though.

Thank you Ralph, But I don't see the agribusiness specialization is mentioned in the UC Davis website.

Not only is there a joint MS/MBA in agricultural and resource economics, but there are a wealth of classes in agriculture and agribusiness you can take while in the MBA program. I believe you can work with them to design an actual specialization - you should contact the school if you're interested.

Thank you Ralph, But I don't see the agribusiness specialization is mentioned in the UC Davis website.

Please, can anybody comment on the reputation and career prospects of 1 year agribusiness MBA offered by Calpoly?
http://mba.calpoly.edu/mba_program.html

It's accredited by the AACSB, which means that the curriculum will be vetted and meet some baseline standards.

One thing to think about:

Because one-year programs are so short, it's generally difficult to fit a concentration into the studies. In the Cal Poly program, for example, you basically get the core management stuff and some agribusiness courses, without much else.

By contrast, the 2-year agribusiness program at Santa Clara would give you much more breadth, including courses in decisionmaking, ethics, and investment analysis, among others. The wider timeframe also allows for internships and immersion trips, which are pretty integral to developing your network in the field.

Think about whether you actually need a concentration - perhaps a 1-year general program would be a better option.

Can anybody advise on the 'International Food and Agribusiness MBA' offered by Royal agricultural university, UK in terms of its reputation, career prospects and international mobility?

The university itself is an old one and as far as I know one the oldest agriculture colleges in the UK. The MBA is certainly a niche program and probably does not have a huge appeal, so you're not going to see this program show up on any top lists or rankings.

If you're looking to transition to the UK from elsewhere and work in agriculture, this degree may or may not help you. My sense is that agricultural organizations in the UK are not as likely to hire international MBAs as other firms, and an MBA is hardly the best route into the agricultural industry anyway.

Depending on your goals, you might look at ranked MBA programs in the country instead - at least that would keep your options open after you graduate.

Thank you Laurie, that makes sense.

It is not showing up in the rankings, may be, because it is a specialized MBA.