The superiority of modern crop varieties is so taken for granted that older cultivars and landraces are typically relegated to the status of seedbank acquisitions. This model of active commercial breeding and seedbanks as reserves is simple and also simplistic. One flaw is that when modern cultivars fail seedbanks are not necessarily able to step in. Their stocks may be genetically degraded, non-viable, or simply insufficient. A further flaw is that seeds are much more than capsules of genetic diversity, their appreciation often requires farming, culinary and medicinal knowledge which is lacking in most seedbank collections. This situational aspect of genetic conservation is widely ignored and explains much of why in situ conservation is underappreciated. And when a hurricane struck the Sunderbans of West Bengal earlier this year it wasn’t government seedbanks or commercial breeders who stepped in to help. The author, Debal Deb, describes how Vrihi, the folk rice seed bank he had founded 14 years ago, made a seminal contribution to restoring the livelihoods of a dozen farmers by providing the valuable seeds of the forgotten rice varieties.
Traditional crop landraces are an important component of sustainable agriculture because their long-term yield stability is superior to most modern varieties. An ample body of evidence exists to indicate that whenever there is a shortage of irrigation water or of fertilizers--due to drought, social problems, or a disruption of the supply network-- “modern crops typically show a reduction in yield that is greater and covers wider areas, compared with folk varieties” (Cleveland et al. 1994). Under optimal farming conditions, some folk varieties may have lower mean yields than high-yield varieties but exhibit considerably higher mean yields in the marginal environments to which they are specifically adapted.
All these differences are amply demonstrated on Basudha farm in a remote corner of West Bengal, India. This farm is the only farm in South Asia where over 600 rice landraces are grown every year for producing seeds. These rice varieties are grown with no agrochemicals and scant irrigation. On the same farm, over 20 other crops, including oil seeds, vegetables, and pulses, are also grown each year. To a modern, “scientifically trained” farmer as well as a professional agronomist, it’s unbelievable that over the past eight years, none of the 610 varieties at Basudha needed any pesticides--including bio-pesticides--to control rice pests and pathogens. The benefit of using varietal mixtures to control diseases and pests has been amply documented in the scientific literature (Winterer et al. 1994; Wolfe 2000; Leung et al. 2003). The secret lies in folk ecological wisdom: biological diversity enhances ecosystem persistence and resilience. Modern ecological research (Folke et al. 2004; Tilman et al. 2006; Allesina and Pascual 2008) supports this wisdom.
If the hardware of sustainable agriculture is crop diversity, the software consists of biodiversity-enhancing farming techniques. The farming technique is the “program” of cultivation and can successfully “run” on appropriate hardware of crop genetic and species diversity. In the absence of the appropriate hardware however, the software of ecological agriculture cannot give good results, simply because the techniques evolved in an empirical base of on-farm biodiversity. Multiple cropping, the use of varietal mixtures, the creation of diverse habitat patches, and the fostering of populations of natural enemies of pests are the most certain means of enhancing agroecosystem complexity. More species and genetic diversity mean greater complexity, which in turn creates greater resilience--that is, the system’s ability to return to its original species composition and structure following environmental perturbations such as pest and disease outbreaks or drought, etc.
Agricultural sustainability consists of long-term productivity, not short-term increase of yield. Ecological agriculture, which seeks to understand and apply ecological principles to farm ecosystems, is the future of modern agriculture. To correct the mistakes committed in the course of industrial agriculture over the past 50 years, it is imperative that the empirical agricultural knowledge of past centuries and the gigantic achievements of ancient farmer-scientists are examined and employed to reestablish connections to the components of the agroecosystem. The problems of agricultural production that arise from the disintegration of agorecosystem complexity can only be solved by restoring this complexity, not by simplifying it with technological fixes.