Crop yield, C and N balance of three types of cropping systems on an ultisol in in northern Lampung.

Three types of cropping systems, cassava-based intercropping, hedgerow intercropping and legume cover crop rotations, were evaluated in 1994–1997 in Northern Lampung, Sumatra. The purpose of this experiment was to quantify the C and N flows returned within and transported out of plots and crop yields of different cropping systems.Cassava-based systems were not stable and yields declined over time. Intercropping cassava with rice increased cassava fresh tuber weight by 5–48% compared to the monocrop-ping system. The hedgerow intercropping gave lower maize, rice, groundnut and cowpea yields than could be obtained in a crop rotation with legume cover crops. Maize grain yields in the 80–20 rice/maize mixture were about 0.4 Mg ha1 in the rice — groundnut rotation and about half as much when intercropped with cassava or hedgerows. Rice yields intercropped with cassava or with hedgerows were about 1 Mg ha1 less in year 2 and 3 than those grown in rotation with groundnut. The rice yield in the first cropping season was only about 1 Mg ha1, but in the second and third year yields in the rice — legume rotation increased to around 2 and around 3 Mg ha1, respectively. This increase occurred despite a decline in soil organic matter content.The cassava-based systems removed much more C (7 Mg ha1 yr-1) than the other systems, while less was returned (about 0.5–2 Mg ha1) to the soil. In the hedgerow intercropping system about 2.5 Mg C ha1 yr1 was returned to the plot as biomass pruning and crop residues and about 1.5 Mg C ha1 yr1 was removed from the plot as yield. In the cover crop rotation 2.6 Mg ha1 yr1 of C was returned to the plot as crop residues plus Mucuna (only the 2nd year) and Cowpea biomass, and about 1.1 Mg ha1 yr1 was removed from the plot. The hedgerow intercropping systems gave an N surplus of about 15–50 kg ha1 yr1 returned to the soil; while the balance was 10–20 kg ha1 yr1 for the cover crop rotation systems and the cassava-based systems showed a negative N budget of about 60 kg ha1 yr1.

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DOI:

https://doi.org/10.1016/S1573-5214(00)80001-9

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