?url_ver=Z39.88-2004&rft_val_fmt=info%3Aofi%2Ffmt%3Akev%3Amtx%3Ajournal&rft.aufirst=R+H&rft.au=Phiri%2C+R+H&rft.aulast=Phiri&rft.atitle=Soil+nitrate+dynamics+in+relation+to+nitrogen+source+and+landscape+position+in+Malawi&rft.title=Agroforestry+Systems&rft.issn=0167-4366&rft.date=1999&rft.volume=47&rft.pages=253-262&rft.issue=1-3&rft.genre=article