The relay interplanted seedling crop likewise places small but increasing demands on the soil. As the first crop gradually fades out of the picture and is finally removed entirely through harvest, the sequential crop continues to advance and the transition is completed. Both low and high technology societies can profit by adopting one or more of the various multicropping techniques. Multiple cropping places heavy demands on the soil and cannot be successful unless the crop is supplied with adequate fertilizer. Many marginal farmers find the purchase of inorganic fertilizers beyond their means, even if obtainable, and should not consider intensive multicropping systems.
Minerals provided by burning cleared land have only temporary value.
On the other hand, many systems of multicropping originated under subsistence farming and can be made to work using available sources of fertilizer. Placing fertilizer in bands between plants or directly in the planting hole are two ways of making more efficient use of fertilizer at hand. Where possible, legumes should be planted for their ability to obtain nitrogen from the air and convert it into forms available to plant roots. The advantages of multicropping include greater use of available solar energy in the dry season, improved pest control, greater insurance against crop failure, better nutritional balance for families because a wider variety of foods is produced, and a more stable farm income. As in any departure from traditional methods, some cautions and hazards may be encountered in switching from mono- to multicropping.