Research at "The Land"

Orginally 28 acres, The Land Institute has now expanded to about 300 acres. To understand why the work of The Land is so different, we may recall that all the major crops of the world are weedy annuals. They produce a small amount of vegetative growth but a high seed yield. Three main strategies used by these plants (alone or in combination) are:

• store a high quantity of food in the seed
• have many seeds
• have the ability to rapidly colonise a disturbed area.

In order to understand how perennials may work in a productive polyculture, Wes Jackson asks four basic questions:

• can perennialism and high yield go together
• can a polyculture of such perennials outyield a monoculture
• can we get such an ecosystem to sponsor its own nitrogen fertility
• can this polyculture control insect pathogens and weeds

These basic questions inform some others which follow from them. What levels of plant production are sustained on the praire, when are the different plant components active amd what are their roles in the grassland community, what are the proportions of legumes, composites and warm season or cool season grasses, how does the vegetation change over timeand what are the phenological, morphological and phsiologicalogical factors which permit coexistance?

Perennial plants domesticated by humans would be analogs of the native prairie.

Currently much of the work of the land is still in the inventory phase. Criteria used in the search for useful plants is their potential for high seed yield, winter hardiness an the ecological role they may play in polycultures (for example, is it a legume?).

Promising plants discovered so far are eastern gama grass, Illinois bundleflower, perennial soybean, giant wild rye and a perennial sorghum. If more assistance was available, Wes would like to work on maximillian sunflower, intermediate wheat grass and hybrids of perennial rye and some relatives of millet.

Eastern gama grass (Tripsacum dactyloides) is a relative of corn. It contains 27 %protein, three time that of zea maize and twice that of wheat. It has 7% fat and is1.8 times higher in methionine than corn and a warm season grass which fixes small quantities of nitrogen. The rhizosphere. of the plant leaks sugar which feeds bacteria in the soil. In selecting for high yield in our crop plants, we have unwittingly selected against sugar leakage, the photosynthate goes to seed instead. We then add a legume to the rotation. Wes Jackson says, "isn't it better to pay the bill with sunlight - the internal control of a system is more energy and materials efficient - it is better to have it in the system than to add legume and plow it in. Wes speculates that a 50-100 yr timeframe may be necessary to develop this grass for use, a long term vision which few people have the stamina to maintain.

Illinois bundleflower is a native legume which produces seed equivalent to the soybean, with 38% protein and 34% carbohydrate. Work is progressing to select for shatter resistance, with the early results suggesting over 2,200 lbs per acre yield. This seems to suggest a positive answer to the question, "can perennialism and high seed yield go together?"

Perennial sorghum yields 175 bushells per acre. Johnson grass crossed with domestic sorghum can produce a race of sorghum with more sets of chromosomes. There is a large genetic variation within Johnson grass so this work has even more potential. A backcross to sorghum did not survive winter, but F1.x F1 gave winter hardiness.

Maximillian sunflower has a seed with 21% oil content. It appears to have useful allelopathic characteristics which inhibit weed growth.

Some basic questions in trying to farm like the prairie include, "can a perennial polyculture overyield, what types of interactions occur between plant species, in what ways can crop species compliment each other, can we promote positive associations without encouraging negative interactions within polyculture designs and does overyielding change from year to year."

Overyielding occurs when a crop mixture yields more per unit area than the components yield when grown in monocultures. It occurs because competition can be less intense between plants of different species than between members of the same species, or one species may even enhance or assist the growth of another.

Plants of different species may produce a canopy which occupies different vertical layers, or the roots may exploit differnt zones within the soil. or they may have differnt nutrient requirements and therefore do not really compete (grasses and legumes?) or they may have differing growing periods. Intercropping in traditional South American growing systems have exploited these characteristics for centuries. An example is the mexican bean-squash-maize polyculture.

The contribution of legumes is better understood, but questions still remain about the extent to which fixation of nitrogen may compensate for N used in plant growth and the removal of harvested product.

The idea that polyculture could manage their own pests, weeds and pathogens is commonly the subject of agroecological studies. Allelopathy is one major mechanism. It is the direct or indirect harmful effect that one plant may have on another, through the production of chemical compounds which escape into the environment. Crop diversity may also provide masking barriers that interfer with colonising, movement, feeding efficiency and reproduction of plant-feeding insects, or may provide an attractive environment for predators.

Disease in crops is often greater where crop genetic uniformity is extreme. Therefore mixing species and genotypes within species can reduce their impact.