This from Mulch-L I thought it would appeal to ecopath people. Whilst mulch-L is a list mostly for sunnier climes than the majority of us live in I thought there was food for thought kathryn > >Aloha, > >A Mulch-L reader suggested we share this edition of The Overstory with you. >We hope you enjoy it. > >Craig Elevitch >AgroForester >PO Box 428 >Holualoa, HI 96725 USA >Tel: 808-324-4427 >Fax: 808-324-4129 >[EMAIL PROTECTED] >http://www.agroforester.com > >::::: The Overstory #42--Improved Fallow with Trees > by Kim Wilkinson and Craig Elevitch ::::: > >Contents: >::::: Improved Fallow ::::: >::::: Improved Fallow Species ::::: >::::: Related Editions of The Overstory ::::: >::::: Web Links ::::: >::::: References ::::: >::::: Publisher Notes ::::: > >::::: Improved Fallow and Land Rehabilitation ::::: > >Given enough time, natural processes will restore productivity to degraded >or damaged land. Traditionally, farmers have used the practice of "fallow" >to allow crop land to rest without crops and be rejuvenated naturally. When >the fallow is enriched with fast-growing trees, shrubs or vines, the >practice is called "improved fallow." Improved fallow is an agroforestry >practice that has its origins in slash-and-burn agriculture. Farmers use >improved fallow to accelerate the process of rehabilitation and thereby >shorten the length of their fallow periods. The technology can be applied to >any agricultural land that is not under cultivation in order to accelerate >recovery, increase nutrient reserves, and improve the potential for future >productivity on the site. > >To create an improved fallow system, farmers scatter seeds or plant >seedlings of fast-growing plants after harvest of the crops from the site. >Normally, nitrogen-fixing plants are used, because they are vigorous, >deep-rooted, tolerant of drought, and have the ability to accumulate >atmospheric nitrogen (see Overstory #4 on Nitrogen Fixing Trees ><http://www.agroforester.com/overstory/overstory4.html>). The trees and >shrubs are left to occupy the site for several months or years. During the >fallow period, the plants accumulate nitrogen from the air and from deep >layers of the soil, and drop their leaf litter to enrich the soil and >conserve moisture. When the trees are removed at the end of the fallow >period, their roots remain in the soil to decompose gradually, releasing >additional nutrients to the subsequent crops. > >The trees and shrubs in the fallow also provide another important service to >the farmer: they fill the space and impede the establishment of undesirable >weeds. Many kinds of invasive and problematic weeds thrive in open, >sunny conditions on vacant land, but do not spread into areas that are >cooler and shadier. The plants that are part of the improved fallow create >conditions that are unfavorable to most problematic weeds, making the >subsequent establishment of crops easier than if the area had to be cleared >of undesirable weeds. > >Benefits of improved fallow: > >* Improve soil fertility >* Accumulate nutrients >* Add organic matter >* Keep down undesirable weeds while land is not under cultivation >* Break up hard soil >* Regulate temperatures (less extremes of hot/cold) >* Provide shade >* Protect from winds >* Reduce erosion >* Encourage or sustain populations of beneficial soil microorganisms >* Break up physical barriers to root growth (rock and hard pan) > >When the trees are removed at the end of the fallow period, they can also >yield products such as firewood or poles for sale or farm use. > >::::: Improved Fallow Species ::::: > >The effectiveness of the fallow in improving the subsequent productivity of >the land depends on many factors. It is important that the land is kept in >fallow long enough for the conditions to improve. The condition of the land >will in part dictate the necessary length of the fallow, as severely >degraded land will need more time than healthier land. The effectiveness of >the species used to regenerate the land is also a key factor. > >The optimal species to use for improved fallow are fast-growing, >deep-rooted, tolerant of drought, easy to establish, and preferably >nitrogen-fixing. There are many species that fit this description. However, >in most cases it is also important that the species be easily removed or >short-lived so as not to interfere with future productivity. This narrows >the list of appropriate species considerably. > >Characteristics of species used: >* nitrogen-fixing and/or produce large amounts of organic matter >* hardy; tolerant of drought and neglect >* easy to establish >* removable or short-lived; will not resprout continually if cut down >* not weedy; will not spread to neighboring crop areas. >* deep rooted >* able to produce useful or marketable by-products such as firewood, poles, >edible seeds, etc. > >Example species used for this purpose: >Inga edulis (Inga, or ice cream bean) >Cajanus cajan (pigeon pea) >Crotalaria sp. (sunn hemp) >Sesbania sesban (sesban) >Samanea saman (monkeypod) >Gliricidia sepium (madre de cacao, rata maton) >Erythrina sp. (E. poeppigiana, E. fusca) >Senna siamea (pheasantwood) > >The links below include photos or descriptions of various improved fallow >systems from around the world. Some examples include: >* Sesbania sesban and Tephrosia vogelii improved fallow land between maize >production in Zambia >* Acacia mangium improved fallow/land rehabilitation in Costa Rica >* Gliricidia sepium improved fallow in Southeast Asia >* Mixed species improved fallow in Amazonia > >::::: Related Editions of The Overstory ::::: >The Overstory #4--Nitrogen Fixing Trees -- A Brief Introduction ><http://www.agroforester.com/overstory/overstory4.html> >The Overstory #20--Five Fertility Principles ><http://www.agroforester.com/overstory/overstory20.html> >The Overstory #22--Pioneering Difficult Sites ><http://www.agroforester.com/overstory/overstory22.html> >The Overstory #28--Microlife ><http://www.agroforester.com/overstory/overstory28.html> >The Overstory #8--Mycorrhizae ><http://www.agroforester.com/overstory/overstory8.html> > >::::: Web Links::::: >Photo and text by ICRAF on improved fallow in Zambia--sesbania and corn ><http://www.cgiar.org/icraf/res_dev/prog_5/tr_mat/slides/ag_tech/5_27.htm> > >Gliricidia improved fallow research in Asia ><http://cres.anu.edu.au/imperata/impab972.htm> > >Alternatives to Slash and Burn (ASB) Program in Amazonia ><http://wwwscas.cit.cornell.edu/ecf3/MyPages/ASB/MTMSafari.html#anchor151781 >2> > ><http://www.winrock.org/forestry/factpub/Slidesho/IMPRVFLW.HTM> >Several photos of improved fallow from FACT Net, including Acacia mangium in >Costa Rica > >An article about solutions for depleted soils ><http://www.worldbank.org/html/cgiar/25years/agro.html> > >::::: References ::::: > >P. Ramachandran Nair, An Introduction to Agroforestry. 1993. Kluwer Academic >Publisher. Amazon.com link: ><http://www.amazon.com/exec/obidos/ISBN=0792321359/agroforestercom/> > >:::::::::::::::::::: >::::: Publisher Notes ::::: > >The Overstory is published by AgroForester, P.O. Box 428, Holualoa, HI >96725 USA Tel: 808-324-4427; Fax: 808-324-4129 <[EMAIL PROTECTED]> ><http://www.agroforester.com> > >Past editions of The Overstory: ><http://www.agroforester.com/overstory/osprev.html> > >Copyright 1999 Craig Elevitch and Kim Wilkinson. For conditions of use >please contact <[EMAIL PROTECTED]> or write to AgroForester at the >address above. > >::::: Subscriptions to The Overstory (NOT MULCH-L) ::::: > >Please send an e-mail to <[EMAIL PROTECTED]> with the subject >"subscribe" (or "unsubscribe") and in the body of the message: > >1) your name >2) e-mail address >3) organization or brief project description >4) your location (country, state) > >Any other information about yourself that you would like to include is very >welcome, as it helps us tailor the newsletter to your needs. **We will never >sell, give or distribute your name to anyone.** >
