National Australia Bank chief executive John Stewart is a strong believer in the view that increasingly affluent Asian communities will fuel much greater demand for agricultural products around the world. Yesterday he committed NAB to an agribusiness banking expansion strategy in the United States, announcing that the bank would pay US$798 million for Great Western Bancorporation.Great Western, which is based in Sioux Falls South Dakota and operates in six mid-western states, has assets of more than US$3.4 billion and 800 employees. The bank has been privately owned for the past 35 years.Local media quoted Great Western management as aiming to grow assets to US$20 billion over five years.Stewart said he saw the acquisition as a springboard for growth of the bank's agribusiness relationship banking model in the US. Stewart has previously described agribusiness as one of NAB's core competencies and one of its drivers of growth.There is a lot of bullish sentiment around agribusiness at the moment. Last week Commonwealth Bank's agribusiness division launched an agribusiness stock index, put together by CommSec's quant research team, with a commentary that said the sector was booming. Commonweath Bank executive general manager agribusiness, Jon Sutton, said: "The consensus outlook for the agri sector is well above the broader market at 25.2 per cent in the coming year. The S&P/ASX 200 is forecast to grow 15.4 per cent."Investors are looking past the impact of the drought and feeling confident about agriculture here and around the globe. There is a need for greater investment in the industry to enable it to keep up with rapidly increasing demand for produce."Stewart said increasing demand for bio-fuels was another factor contributing to the bullish outlook for the sector.Stewart said NAB's acquisition of Great Western would involve capital initiatives, which may include changes to the dividend reinvestment plan, such as removing the cap or introducing a slight discount on the price. There was also a possibility of using hybrid capital.The acquisition is expected to be 0.5 per cent earnings per share dilutive in year one and EPS neutral by year three. It will have no impact on dividends per share.Stewart said US farmers grew similar crops and took a similar approach to farming as their Australian counterparts. They had similar financial needs. He said the US agribusiness banking market was fragmented and this presented a growth opportunity for a well capitalised bank with a good product set.He said Great Western had no exposure to sub-prime loans.