s:777:"TI Roots as part of the Carbon and Nitrogen input and output of three types of cropping systems on an Ultisol in North Lampung 
AU Hairiah, D.K. 
AU Cadisch G 
AU van Noordwijk, M. 
AB Yields of annual food crops typically decline with time after conversion of forest (fallows) in the humid tropics, along with a declining soil organic matter content. Application of organic matter particularly in combination with inorganic fertilizers, may maintain a high crop production. However, the availability of organic materials such as (green) manure or crop residues is limited, while fertilizer use is often not within the financial possibilities of small farmers. Understanding the dynamics of C and N in such systems may help to understand the options for soil management. 
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