Soil Erosion and Conservation As Affected by Land Use and Land Tenure, El Pital Watershed, Nicaragua

Fr(Ht~ C(~'\'f:f" c:-;!.r-:~;;:' f5hnta?::)H H'!. ~he ~lppt:r pn;-:-jf~!: \":-;: :J:-:': f.l. r:::.:::J ;.;;/:!kr:~h).:'d ~h;:-:~ ;:., m:.;.;;\;.;.~:;:'(:. '::~n(~~ .. : var~t:t)' \,i.' ;:,(:::: \."-':.'(S!::tV:H:,(>H h>.:imiqt:cs ':-'~1(: c{':r:::··;;, trf:(;~ ~H"(:· :;h::d~:d by ({vi; :rr:(: ·;i.mh<:f lrc(:'''; Th:: :'.:. ... i-: ~::, f:.J;{:"!~,:r rr:)te'(;~(:d b.\· !;;.~;i;.n{:n.~;~:i.':;:· ·:_:·:.. -:·:!:;:.. ... ~~t~n·r:_:.;_ii.\;:·: "'-'.';':'):1' ':;'0[1:;. SOIL EROSION AND CONSERVATION AS AFFECTED BY LAND USE AND LAND TENURE, EL PITAL WATERSHED, NICARAGUA

Amy Purvis Thurow ' Matilde de los Angeles Somaniba-Chang,' Thomas Lee Thurow,' and

'National Agriculture University Managua, Nicaragua

'Department of Rangeland Ecology and Management Texas A&M University College Station, Texas 11843-2126 USA

Global Bureau, US This work was, in part, made possible through support provided by the LAG-G-OO-91-OOO2-OO Agency for International Development, under the terms of Grant No. reflect the views of The opinions expressed herein are those of the authors and do not necessarily research in the U.S. Agency for International Development Soil and water conservation by numerous colleagues Nicaragua has benefitted from the expertise and friendship extended Agriculture University with shared interests. Recognition is given to colleagues at the National published data. We also (UNA) for their assistance during the field work and in procurement of the Nicaraguan thank directors and technical personnel of the El Pita! Agroforestry Project, the National Union of Agricultural Technology Institute (lNTA) of the Masatepe headquarters, of Nicaraguan Coffee Farmers and Cattle Ranchers (UNAG) in Masaya and Granada, the Union Economic Community Producers (UNlCAFE) of the Masatepe headquarters and the European to the 135 fiumen who CEE-ALA project in Region IV. We also express our sincere thanks more copies of this kindly participated in the interviews that were part of this study. For please contact Dr. technical bulletin or further information about the CRSP research program, College Station, TX Tony Juo, Texas A&M University, Department of Soil and Crop Sciences, Renewable Resources. 11843-2474. As of August, 1999, Tom is Head of the Department of Dum Drive, Laramie, University of Wyoming. Amy and Tom Thurow can be reached at 1071 WY 82012 or .

UNITED STATES AGENCY FOR INTERNATIONAL DEVELOPMENT PROGRAM SOIL MANAGEMENT COLLABORATIVE RESEARCH SUPPORT TEXAS A&M UNIVERSITY

TECHNICAL BULLETIN Number 99-3

December, 1999 SOIL EROSION AND CONSERVATION AS AFFECTED BY LAND USE AND LAND TENURE, EL PIT AL WATERSHED, NICARAGUA

INTRODUCTION produetion (e.g., beans, maize) than previously. Second, the portion of a f.um devoted to annual Throughout the tropics, water induced soil crop produetion is in~' rdated to f.um size. erosion threatens sustainable agricultural produc Farm fragmentation associated with tion on steeplands. Nicaragua is the largest agrarian reform and inheritance customs bas country in Central America, with the region' s contributed to the increase in small farms, hcuce highest annual population growth rate, 3.40/0, and there bas been an associated increase in its lowest average per-capita annual income level, cultivation of annual crops, leading to an increase US $420 (The Economist Intelligence Unit 1999). in erosion hazard. Soil consemltion progr.uns Agriculture is the largest sector in the targeted at agrarian reform COJIlDIImities ha\'C Nicaraguan economy. An estimated 7.7 million been successful in proliloong the use of hectares in Nicaragua have been degraded by conservation practices, thus reducing erosion water erosion (IRENA-ECOT-PAF 1994). hazard. Use of geographic information S}'S1anS Farrners with small land holdings make a (GIS), which enable simultaneous anal}'Sis of substantial contribution to the agrieuIturaJ biophysical and land tenure paaems, can aid in economy; many of these small fanns are located targeting where soil consc:n"ation efforts ",ill on steeplands with slopes from 10% to 40%. 1be likely }ield the greatest reIum on in...... ". EI pita] watershed is typical of the many steepland regions in Nicaragua where deleterious effects of Watersbed-scale analysis erosion are increasingly evident. AnaJysis of soil erosion pre- 5 over Overview time at a watershed scale takes into accounI the interrelated biophysical, socioe<:onomi<:, and This study applied Geographic institutional factors which influence natura1 Information Systems (GIS) tools to a combination resource management decisions and OIrtcomes of n:mote-sensed mapping data (1968 and 1981) (Thurow and Juo 1995). Traditional anaJysis of and interview data (1996) to estimate how public and printe in\1:Slmeiits in soil estimated annual soil losses from erosion have conservation ernphasi2es how erosion ad\useI}' changed in the EI pita! watershed over a 28-}"ear affects farmers, through declining crop ~"icIds and period. Changes in land tenure, and associated losses in soil produetivity over time. changes in land use, were the main factors driving A watershed approach also takes into increases in estimated erosion hazard from 1968 account the off-site effects of soil erosion. to 1996. Some observations concerning patterns including drainage disruption, gull)ing of roads, of adoption of soil conservation practices in the EI eutrophication of \Wfer\\."3~'S, siltation ofdams and pita] watershed were profiled, based on interview'S channels, loss of reservoir stcnge capacity, with \35 farmers in 1996. increased flooding risk. loss of wildlife habitat, Evidence from this study supports two damage to public health. and increased water over-arching conclusions. First, erosion hazard treatmer1t costs (PimertteI ct al. 1995). VlDiriomo. suffered the most serious losses in proportion to their assets (The Economist Intelligence Unit

1999). The research results reported here have a Honduras role to play in guiding the selection among future soil conservation investment options, in order to mitigate against risks associated with extreme climatic events. Nicaragua Land-use planning using GIS tools ~KE MANAGUA MANAGUA-rJ,-/ STUCY_.~\ To take action at a watershed scale AREA requires land use planning, the systematic PACIFIC OCEAN assessment of land and water potential, alternatives for land use, and socioeconomic Costa Rica conditions, in order to identify land use options. The aim of land use planning is to select land use patterns to best meet the needs of people today Figure 1. Location ofthe EI Pital watershed while also safeguarding natural resources for the future. The discharge area for the Mombacho In considering complex land-use options, sub-basin is 77 km'. Its drainage pattern is sub Geographic Information System (GIS) tools are dendritric with four ephemeral streams; the water powerful in (I) generating efficient and effective in these streams usually infiltrates into the views of databases that describe land records, (2) pyroclastic depositions of Mombacho volcano. integrating the land data in ways that foster The Mombacho sub-basin experiences runoff only understanding of relationships, and (3) handling during extreme flood events. The Diriomo sub transactional updating of land data to maintain basin is 88 km' and its drainage involves seven current information (Dangermond 1989). ephemeral streams (MARENA 1993). Furthermore, maps generated using GIS tools Seventeen percent of the watershed has slopes allow for comparison and analysis of spatial and greater than 10%, and five percent has slopes temporal patterns (Selman 1991; Brown et a1. greater than 20%. 1994). The ability to consider several data sets The 1994 population of the EI Pital simultaneously, and to display numerous complex watershed was 58,505; its population density was relationships on a single map, makes GIS analysis 148 people per km'. Approximately 62% of El a powerful aid for policy discussions. Pital residents live in small communities, the remaining 38% live on their farms in rural areas.

2 The four IDIIDicipalities in the Masaya Depanmeut were beneficiaries of agrarian moon (BAR) v.iIo are Catarina, Niquinohomo, San Juan de Oriente, lived on 60 farm coopea ativcs. In 1996 farm and San Jose de Masatepe. The four cooperatives controlled 6,457 hectares. municipalities in the Granada Department are approximately 33% of the land in agriculture in Oiriomo, Diria, Granada, and Nandaime. the El Pita! "Watershed. Large Q ilUlacial farms in Latin America Climate which support only a few pcopIe dewte a n:latively small proportion of tbcir land farmed to As cbaracterized by the Koeppen Climatic subsistence annuaJ crops, such as com aDd beans. Classification, the watershed has a humid and dry Annual crops do not prolCd the soil from c:rosicn tropical climate (MARENA 1993). Annual as well as pemmial crops. pasture aDd forest. precipitation averages approximately I ,500 mm. Before the Land Reform Law was implcmemed, The miny season occurs from May to October. most large land holdings in Nicaragua were The altitude varies from 160 to I, I 00 meters. operated as W1wnercial farms cmpbasizing Elevation has a great influence over mean pemmial crops (e.g., coffee. fruit trees), tn'l:StoCk daily temperature which varies in the watershed and timber production. The~' c:rom'e from J3 ° C in December to 25°C in April at the steeplands were usuaJly managed as pasture or highest elevation, and from 26 °C in December to forest 32"C in April at the lowest elevation (Lopez and Agrarian moon within the v.ata shed Gonzalez 1994). The miny season (May to took place during the Sandanista rewIution October) is divided into two growing periods, (1979-1990). Before 1979, the agricultural primera (May to August) and postera (September c:cooomy in Nicaragua was dcminated by a to November). There is a dry period from mid private, modern sector of relatively few "aIth). July to mid-August, the Ct11Iicula. landowners and a relatively large. poor peasant sector. The Land Reform Law of 1981 formally Geology ud soils legalized the process of confiso aling farm land that was not being used to its pcemtial (Spoor The El Pita! "Watershed is part of the 1995). The confiscatims targeted large private southwest Nicaragua depression flank. The farms owned by the Samoza family (the family geomorphology of soils in the watershed is who cmtroIled the political s)'StI:III prior to 1979) diverse, with ten soils series represented from the and their political allies. Confiscated land "'as valley to the mountains. The basin has mainly redistributed to landless peasants "iIo were moderately to well-drained soi1s. The parentaJ organized into farm cooperaIive units. materiaJ of the soils includes basaltic rocks, Cooperative boJdings of farm land were volcanic ashes, alluvial sediment, and limestone. nonexistent in 1978, but quiddy inacased to The topsoil depth ranges from deep (>80 em) in occupy 23.4% ofagricultural land in Nicaragua in lowlands and on well-vegetated hillsides to 1981, and 39.7"10 in 1988. shallow (<30 em) on intensively-used steeplands. Implcmillalion of the Land Reform Law The two dominant soil texture types in the in the 1980s meant that IIUI1ICIOUS pra-iously watershed are sandy loam and clay loam. The IandIcss families - some from within E1 Pita! organic matter content ranges from 3% to 9%, watershed, some from urban an:as or odIcr turaI indicating stable soil structure (MARENA 1993). regions - wen: CIIIXJUJ38ed to establish subsistcooe IevcI farm Cilll:ijliises on plots LudteDure subdivided from the confiscated large farms. Farm cooperatives were formed aDd used as the In 1996 private land holdings occupied institntional mechanism for 01 dJtS1Jating the 7golo of the El Pita! watershed, the ranaining 21% rescttlement process. Though the families v.iIo

3 joined fann cooperatives were not given secure after the harvest. Beans are planted at the onset of title to the particular plots they farmed, the the postera. The row width for beans is 40 em; redistribution of land into cooperatives is two seeds are planted per hole at a distance of 10 considered a permanent arrangement for em. The bean harvest occurs at the end of the cooperative members in good standing. postera. Assignment of plots within the cooperative For sorghum production, seeds are landholding, however, is sometimes changed from planted at the onset of the primera. Like com, year to year. Accordingly, cooperative members sorghum is produced for commercial markets; have an incentive to contribute labor to the accordingly, farmers use fertilizer, herbicides, and cooperative's landscape-level conservation pesticides to manage this crop. Only the follicle projects, whether or not working for the common is harvested at the end of the primera. The stalks good yields direct and inunediate payoffs on their are left in the soil and a second grain crop is particular plot. harvested at the end of the postera. A secano (rainfed) system is used in rice Cropping systems production. Tractors are used in land preparation and seeds are planted in continuous rows at the To understand the context within which beginning of the postera. Fertilizers and land-tenure and land-use changes have occurred pesticides are applied at several intervals during in the El Pital watershed, a characterization is the growing season, herbicides are used for weed presented of its five distinct categories of control. The rice crop is a cash crop, little is used cropping systems: grain production on the plains, for family consumption. grain production on the hillsides, production of a diverse array of crops, coffee production, and Hillside grain production livestock production. Oxen are used in land preparation, and Luwland grain production vegetation is cleared using manual labor, herbicides, or fire. Crops include rotations or In the plains, grain is produced in three intercropping of corn and beans, com-beans different cropping systems, (I) rotation or cassava (Manihot esculenta Crantz), or com intercropping of corn and beans, (2) monoculture beans-rice. of sorghum, and (3) monoculture of rice (Oryza The com-beans rotation is normally com sativa L.). Generally, tractors are used for in primera and beans in postera. Crops are plowing and the crop is planted using oxen to planted in rows made by an ox-drawn plow or in make a furrow for the seed. holes dug manually with a digging stick For corn and beans production, land is (espeque). In a com-bean intercropping field, cleared in April. The crops are planted when either alternate rows or a randomized scheme are primera rains come in May. Corn rows are used. In the alternate row system, the distance spaced 80 em; within each row, two seeds are between rows is 80 em, the spacing of plants planted per hole, spaced 30 em apart. The rate within a row is 30 cm between com and 20 em and timing of fertilizer and pesticide application between beans. In the espeque system, the depends on perceived need and availability of distance between holes is one meter. cash. Weed control is done either manually or The cultivation of rice is done using either with herbicides. Corn is harvested during the the row system or the espeque system. In general, canicula. Corn staIks are either chopped for agrichemicaIs are not used with espeque livestock feed or piled and burned. Corn stalks cultivation, because farmers who use this labor are removed to reduce the risk of pest infestations intensive system are almost always poor. If cash in the next crop. The field is cleared and plowed is available, some fertilizer and some pesticides or

4 herbicides may be applied. Cassava is planb:d traditionaI shadow systan aDd a IIIIlI"C m:enl with 30 em between rows aDd 50 em ~ shadc-fRe system. p1antings. Cassava is primarily produced for Fruit tm:s or timber tm:s are used for home consumption, only occasional surplus is shade in uaditionaI shadow coffee production. sold in local markets. Shade serves aIIows the beans to mature s1owIy, to improve coffee flavor ricbocss. Use of shade Diverse crops productimt also Ia!gtbens the time period for bean ripening so that a few laborers are emp~'ed over a Some f.mns specialize aDd produce fruits, protracted period. WJtbout shade, coffi:e gIO"us medicinal plants, omamcntal plants, and/or who operate using a fuJI ScaSOll system ttmpdC vegetables for both family consumption aDd local for scarce labor during an intense SC\ua1-week markets. Fruits produced include lemons (Citrus harvest period. In addition. shade tn:cs generate limon (L.) Dunn.), sweet oranges (Citrus sinensis fuel wood, timber, fruit., aDd spices. Some shade (l.) Osbeck), tangerines (Citrus reticulata tm:s assist in maintenance of soil fertility through BIanco), mangos (Mangifera indica L.), avocados nitrogen fixation (Lopez aDd Gonza\c:z 1994). (Persea americana Mill), guavas (Psidium Shade cover also dissipates raindrop energy aDd guajava L.), pineapples (Ananas comosus (L.) thereby reduces erosion bazaJd. Merr.), papayas (Carica papaya L.), granadiIIa Tree species used in traditionaI sbada\lo.' (Passijlora quadrangularis L.), passion fruit coffee plantations include cedar (Cedrrla odorakl (Passijlora edulis Sims), pithaya (Cereus sp.), L.), acetuDO (SiltlClrollba glauco L.l, Iaurd melon (Cucumis melo L.), aDd various types of (Cordia alliodora L.), guaba (/nga dmsijlora). bananas or plantains (Musa spp.). Vegetables genizaro (Pithecellobium saltlCl1f (Jacq.). include ",ater squash (Sechium edule (Jacq.) Sw.), cbilamate (Ficus isophlebia), gllanacaste summer squash (Cucurbita pepa L.), tomato (Enterolobium cyclocarptmt (Jacq.) Griseb). aDd (Lycopersicum esculentum MilI.), taro root fruit tm:s like avocado, Ic:mon, zapote (Poutena (Xanthosoma sagittifolium (L.) Schott), aDd sapota (Jacq. H.E. Moore), tamarind (TaltlClnndus cassava. Medicinal plants include cbarnomile indica L.), aDd ,,'arious banana species. The (Anthemis nobilis L.), lemon grass (Cymbopagon dominant tm:s tend to be tall timber species that citratus L.), aloe (Aloe vera (L.) N.l. Bunn), aDd also fix nib~. The canopy oftraditionaI coffee sour orange (Citrus auratium L.). plantations cr:ates a micro-dimate with IIIIlI"C These crops are planted either in stable ten ipCi anae aDd bumiditv• than similar monocu1tures or in home gardens. A home nnsbaded plots. The Iittc:r from these tn:cs is garden is an array of plants grown adjacent to the _intaom as a mukh covering the soil surf.Ice. home of the farmer, usually smaller than one Trees are pruned at the bqsi,g.i"g of the prl_ro. hectare. The primary emphasis is production for The pruned \eaves aDd smaIl braDCbcs add to the home consumption aDd for cash between harvests mulch layer. of other crops. Organic fertilizer produced on On coffi:e p\anlatims using the new fimn is often used. MonocuItures. on the other production system, fruit trees are prewIem - in band, are market-

5 a barrier to soil erosion and supplying a source of such as tropical kudzu (Pueraria phaseoloides organic fertilizer. (Roxb.) Benth.) and cowpea (Vigna sinenis L.) Traditional shadow coffee production Trees dispersed in the grassland are used for techniques are prevalent in the El Mombacho forage, shade, fuelwood, and as posts. These trees region, where Caturra, Catuai, and Mundo Novo were established by natural regeneration or were coffee varieties are prevalent. The other left when the forest was cleared. comarcos with coffee production have almost an equal mix of traditional and newer non-shade Soil conservation plantations, and most often grow Caturra and Bourbon varieties. Traditional farming systems in the El pita! watershed incorporate some soil and water Livestock production conservation practices. Governmental and non governmental organizations have also established Farmers raise livestock for milk and meat. local technical assistance projects to promote the In the El Pita! watershed, there are (1) small farms use of additional agronomic and mechanical which have ten or fewer cattle for family conservation practices. Agronomic practices have consumption and occasional sale and (2) large proven most effective on gentle slopes of less than commercial farms with hundreds of cattle. 12% (Sheng 1989). On steep slopes in the tropics, Grain crops rather than livestock are the agronomic practices are most effective used in primary source of farm income for farmers with conjunction with mechanical structures, and smaIl land holdings (five to fifteen manzanas, i.e. neither are as effective if used separately. 3.5 to 10.5 ha). The role of cattle in the small scale farming system is primarily milk Cover crops and green manure production. Cattle are fed available grass, supplemented by either rental or free access to In the EI Pital watershed, cover cropping pasture on neighbors' fallow land. and green manure are a combined practice. Cover On large commercial farms (100 to 500 crops are either planted after an annual crop has manzanas, i.e. 70 to 350 ha), milk andlor meat had a chance to become well established or after production is the primary farm income earner. harvest. Cover crops protect soil from direct Where cattle are raised for meat, cattle graze on raindrop impact. Subsequently, they are plowed native or introduced grasses in extensivel y into the soil to improve structure and fertility. managed pasture systems. In contrast, a milk Leguminous species such as velvet bean (Mucina production system is more intensive and uses pruriens L.) and tropical kudzu are common cover purchased inputs including feed supplements. In crops and are effective as organic fertilizers. both the milk and meat production systems, cattle primarily graze. Vegetative barriers On intensive milk production farms, some hay is cut for dry season use and sometimes fresh Vegetative barriers are usually planted in grass is cut for stable-feeding. The most common conjunction with terraces. Live barriers are grasses used are bermuda grass (Cynodon formed by planting either woody species, grasses, dactylon (L.) Pers), pata de gallo (Digitaria or cash crops. The base of these plants obstructs sanguinalis (L.) Scop.), and buffel grass overland flow and stabilizes the bunds in terraces. (Cenchrus cilaris L.). Elephant grass or napier Plants most commonly used as vegetative barriers grass (Pennisetum purpureum Schumach.) and in the El Pital watershed include madero negro, gamba grass (Andropogon gayanus Kunth) are leucaena, pigeon pea (Cajanus cajan L.), napier used in cut-and-carry feeding systems. The grass, or sugar cane. farmers also use some leguminous forage crops

6 subsistence needs and many Latin American Plate I: Many poor peasants depend on the steep lands for their needs of their urban populations (e.g .. countries rely heavily on steepland production to meet the food security sorghum - produced in Honduras an:: on USAID (1980) estimated that 75% of the basic grains - maize. beans. steeplands).

on the same hillside pictured in Plate \. Plate 2: Landslides that occurred during Hurricane Mitch in 1999 for the sake of meeting the regions food Since customs and poliCies directly or indirectly result in deforestation to foster adoption of soil and water production needs there is a corresponding need for the government The Soil Management CRSP is documenting conservation practices that will aid sustainable use of these lands. water conservation options (e.f.• Thurow the biophysical and economic viability of various steepland soil and and Smith 1998. Toness et al. 1998). Plate 3: Runoff plots used to collect data needed to calibrate various components of the Universal Soil Loss Equation for the EI Pital region.

Plate 4: Much of the land in the region is plowed using teams of oxen prior to the planting maize. In the background is one of the flumes being used to relate runoff plot data (plate 3) to field scale runoff, soil and nutrient loss data. Traditional farming practices are being evaluated against various soil and water conservation treatments to help determine the return on investment associated with installing and maintaining conservation treatments. Sur/ace mulching steepland sites, contour tillage aIooe docs not significant1y reduce soil Joss and runoff (Sbcug Surfuce mulching practices are used to 1989). dissipate the erosive energy of raindrop impact and overland flow. Some fanners leave crop residues after harvest. Others use pruned materiaI from live barriers or live fences as cover. In There are three variants of CUJSCn.-ation traditional fanning systems, crop residues were tillage practiced in the EI PitaJ watershed. One is cut, piled, and burned to kill pests and weed a traditional fanning method (the ~spet{ll" seeds. Mulch was a conservation practice method), two others were introduced relatively introduced relatively recently by outside recently (minimum tillage and no-till) The organizations working in the EI Pital watershed. espeque method invol\'eS slashing weeds with a machete and leaVing these plant residues 00 the Multipl~ cropping field. To plant seeds, a stick is used to make a hole in the ground, and through the residues. In Multiple cropping is a traditional practice. contrast, in uaditionaI fanning ~-stcms.. fanners It can be as simple as planting com and beans not using the espcque method burned weeds together or it can be a complex, heterogenous mix befure or after cutting them. Burning left the soil of species used in a home garden. Crop susceptible to erosioo from intense rains at the associations can be spatial or temporal. beginning of the pnmero (Smith 1991) Intercropping invol\'eS strips of different crops Minimum tillage involves using the being alternated. Mixed cropping involves rows minimum possible passes of a plow to p1ant a with two or more crops planted together. Relay crop, in contrast v.~ COIM:IIIiooaI pkM"ing cropping is when one crop is planted first, and the practices v.bere muItiple passes are used No-tilI other is planted after the first crop flowers. The planting involves slashing v.eeds or applyiDa most common annual crop associations are com herbicides, leaving the plant residue from killed beans, com-beans-cassava, beans-plantain weeds 00 the soil and using spcc:iaI 9¥ding cassava. Multiple cropping protects soil by equipment to plant a crop. Normally, Ibis ...... tine increasing crop cover and enhanced amount and equipment must be pulled by a tJactor, but diversity of production. recently a seeder was introduced which can be pushed without mechanical traction. N

7 enlarge with sediment accumulation behind live database were collected from plots on gentle to barriers. Soil accumulation is aided by tbe rolling slopes, mainly in tbe midwestern United practice of placing branches and plant residues on States (Hudson 1995). tbe uphill side of tbe live barriers. Terracing was In sum, USLE soil loss estimates for introduced in tbe Pacific region of Nicaragua in tropical steep land sites are most appropriately tbe 1960s when numerous farmers planted cotton interpreted not as absolute values but ratber as a and invested in tbe technology package required basis for comparing tbe relative effects of land to support successful cotton production. use, cropping systems and soil conservation practices witbin a particular study area. Individual basins Empirical measurements or observations of six factors are used to estimate tbe average soil Individual basins are mecbanical practices loss from a field (A), usually in tons per acre per primarily used on traditional coffee plantations in year, using tbe USLE equation: rainfall erosivity tbe EI Pital watershed. They are catchments (R), soil erodibility (K), slope length (L), slope which help to retain runoff, tbereby improving steepness (S), cover crops and management (C), soil moisture content and nutrient retention. and farming and conservation practices (P). The Usually cover cropping, mulching, and/or first four factors (R, K, L and S) are physical composting is used in conjunction witb individual characteristics intrinsic to particular sites which basins. do not change over time, tbe last two factors (C and P) are affected by farmers' land use decisions. ESTIMATING ANNUAL SOIL LOSS Data on physical characteristics and on farmers' behavior are discussed in tum. The Universal Soil Loss Equation (USLE), an empirically-based model developed Physical factors which affect erosion for prediction of erosion hazard in tbe United States (Wischmeier and Smitb 1978), was applied In applying tbe USLE to estimate erosion to compare estimated annual soil losses over time hazard in the EI Pital watershed, the same in tbe EI Pita1 watershed. Worldwide, tbe USLE measurements of tbe intrinsic physical site has become tbe most commonly used soil characteristics were used to compare 1968, 1987, assessment tool (Renard et al. 1996). and I 996 conditions. Two caveats apply to interpretation of USLE-derived soil loss estimates for tropical Rainfall erosivity factor (R) steeplands. First, its soil loss estimates are considered long-term annual averages, the Annual rainfall erosivity (R) is tbe maintained assumption of tbe USLE model being average annual sum of individual erosion index tbat over- and under-estimates of soil loss from values (EI,o) for a particular location. The E individual sturrns will balance out over tbe long component is tbe total kinetic energy for an run (Wischmeier 1976). Due to high-energy individual storm event and 1'0 is tbe maximum 30- rainfall conditions in Latin America, combined minute intensity of the storm event (Wischmeier witb attributes of soils common to the tropics, and Smith 1978). Simply put, tbe R factor for a however, tbis maintained assumption is violated particular site represents tbe amount, intensity and and, accordingly, tbe USLE model tends to over duration of rainstorms for a particular site (Batie predict erosion on cultivated tropical steeplands 1984). (Smith 1997). Second, tbe slope factor in tbe To calculate tbe R factor for sites in tbe EI USLE was developed for modeling soil loss on Pital watershed, regional observations tbat cropland witb slopes less tban 16%, because tbe correlate mean annual precipitation (mm) were empirical observations which comprise its applied to values of rainfall erosivity delineated

8 the slope cffi:cL Soil loss iacR:ases on aerial photographs from 1968 (1:30,000) and cover oftSecs increases than as L iacR:ases from 1987 (1:25,000) by appl)ing GIS tools using more rapidly as S et ai, 1996), an SI-metric unit (Mj-mmlha/brlyr), The annual (Renard the El Pita! watershed, the LS factors precipitation isoheyts of the watershed were used For calculated using a slope map, assuming a to delimit rain erosi,,~ty by site (MARENA 1993, were of 100m \\iIen app/}ing the Smith 1996) standard \eogtb USLE-LS formula (W&luncier and Smith 1978) (1 :50,(00) \\-ere used m Soil uodibility factor (K) Topographic maps characterizing slope, The soil erodibility factor (K) indicates which affect a osioa susceptibility to erosion of the soil types Farmers' choices comprising the watershed, To estimate the soil's how erosion hazard has resistance to being moved by erosive forces, K is To estimate time in the watershed, data on expressed as the rate of erosion per unit of the changed over decisions about cover crops rainfall erosion index (EI) for a plot 72.6 feet in changes in farmers' and managemeut, and cooservatioo bdJon-ior, lengtb \\~ a 9% slope, tilled up and do\\n in maps (1968 and 1987) and continuous fullow (Wischmeier and Smith 1978), "'I:fC collected from \\~ farmers (1996), To assign soil types to sites in the El pita! from ~~ews watershed. a soil in,'eDtory at the comarca level factor (0 was used (MARENA 1993), All sites in the El Covu and manag_ Pita! watershed are either from the Niquinhomo crop cover and managemmt factor series or from the Diriomo series, Mendoza and The a ratio of the soil loss from a 6eId of ccr1ain Rivas (1996) calculated the K factor for three (C) is compared \\~ an years on three runoff plots located witbin the EI eropping management practices c1ean-tilled in continuous faII

The P factor estimates the ratio of soil loss on a field with certain tillage practices to soil loss on a field under straight row plowing up-and down the slope (Batie 1984). In this analysis of t.'le EI Pita! watershed, P factors were not used due to a lack of sufficient site-specific data regarding the effectiveness of the soil conservation practices being used. Furthermore, use of some conservation practices would have been difficult to discern from aerial photographs.

CHANGES IN SOIL LOSS IN EL PITAL r-;O.j WATERSHED -""2 0 11 OVER TIME 1."to·a 1:150000 Geologic erosion is the soil loss that would be expected to occur without the influence Figure 3. Average percentage slopes of human land use, maintained in natural on cropland in the EI Pital watershed vegetation (Figure 2).

A comparison of Figures 2 and 3 suggests that without human activity, severe erosion would be occurring in the EI Pita! watershed on less than 1 % of the watershed, only on naturally unstable sites where slopes are steepest. Only one of the five USLE factors used to estimate annual soil loss in the EI Pita! watershed .. varied; for 1968, 1987, and 1996 the R, K, L, and S factors (estimates describing intrinsic physical factors) were unchanged over time. Only the C factor, crop cover and management, '. changed. In sum, it is human activity which has been the major factor in the ...... ~tT...... ,., transformation of the O i ,...... ' El Pita! watershed into a region with significant 1:1toOOO and increasing erosion hazard. Figure 4 depicts how estimated annual soil loss has changed from 1968, to 1987, to 1996. Comarca boundaries are Figure 2. Estimated geologic erosion, traced in the three maps comprising Figure 4. EI Pita! watershed, Nicaragua

10 1968 1987

1996

3\ { r~. , " 10...... \

5 ~~\ ; I7"--::: '<, 11\., ""-,2--> ; -" I ' 'r ; ( , / .~'3' ,/'/ / ~14j ,~i i l 15 ~ \~ ,.-2· San JaM_ on... \ ,~ ..4-a~ .... '·PllDo..m.dD- •• s.n.JDM 1 • EI eo.,oa.r$"""" 17 \ .-s.no.ga. to· Yeracrur Estmated Soil Erosion (TonsIhaIyr) I·_-1 , • JoM ..... Etc:obw 12 -a Womb-=M .0-10 f)·uG,.... .10-20 ,'''·loIl~...... ll1-eu.ua~ .20-40 11· Dolores .40

Figure 4. Estimated annual soil loss (tooslbectarelyear) "imiD Ibe COIIUU'QS ollbe EI PitaI watersbed, in 1968, 1987, and 1996.

'." N

E s

Portion of Land Devoted to Annual Crops (%) _0-10 _10-20 _20-40 _40-60 1 :160000

Figure 5. Percentage of cropland planted to annual crops, by comarca, in the EI PitaI watershed Table 1 presents the changes in estimated watershed wen: raluced by 51%, 62%, and 6W.. annual soil loss in the EI pita! watershed by respc:ctiveIy, based 00 aoaIysis of aerial comarca photographs combined with use of GIS tools. Concurrcrtly, from 1968 to 1987, the proportioo T .... l. A...... __...... DPIIoI_ 1 ___ .. __I of the El Pita! ",,-atersbcd in annual crops increased 1 01 I ~( •• by 29"10 and the proportion in pen:nniaI crops Ell 2 '-...... increased by 140/.. Gtass dcmjmr..t r.mgdand (-,....) (usuaIly an ecological succcssionary Slate 00 1'" 1'" 1'" cooIoII< cutJbumed and grazed forest land or &Ilow c...... cultivated land) increased by 49% from 1968 to DoIons • • • J 1987. By 1996, an CSfirnatr1I W,{, to 60% ofthe c...-~ Jl 3 3 1 land area was planted to annual crops in over half LooR ._- 19 30 15 4 the c:oman:as comprising the El Pita! ..-atersbcd DM_ 37 31 JI , (Figure 5). A comparison of the 1987 and 1996 maps from Figure 4 with Figure 5 suggats that LaG. •• 37 JI 30 4 CSfirnatr1I erosioo hazard increased most rapidly !"" ill I 39 18 14 5 from 1987 to 1996 in coman:as ..-here !ben: ...-as rapid change from extcnsn-e land uses and SoaJ.uM-,.. 4J Jl l' 18 perennia1 crops to predominantly annual crops, "-"&ria 43 16 15 0 even 00 steeplands. As land use shifts to annual _huQriaOe 50 36 JI J crops from forest, rangeland, and pen:nniaI crops. erosioo hazard increases dramatically; these Dr_ 51 J7 n 5 increases are most dramatic 00 cropland ...-ith v..-.... 51 n 16 , steep slopes (Figure 6).

64 n JI -~ • Increasin& numben of sma"" farms DC.,..... so ... 36 • HojaCWc- fa JJ J7 4 population in the El Pita! watershed was estimated by n:giooaI go"CUUDtut officials to be J_B.F..KHu 101 56 35 • increasing at 1east as fast as the 3.4% per year ..... 0--0 II 36 1• estimated population growth rate for Nicar.Igua. I" One factor that contribulai to the rapid population l3J 50 43 J -..... incmIse the El Pita! watershed was that il ..-as the destination for sc:veraI rdocatioo efforts In 1996, elevm of the 17 c:oman:as in the amriatexl with agrarian reform in the 1980s. The El Pita! watershed bad estimated erosioo hazard combinatioo of population JlRSSUI'C, inbailance above 40 tons per acre per year. By comparison, customs, and agrarian reform, bas meant an in 1968 only one of the 17 coman:as bad erosioo increasing number of small, subsisrmce fmns in hazard above 40 tons per acre per year. El Pita! watershed, as e1scwbcre in Nicar.Igua. This demographic tn:nd bas impoItml More cu;tivation of UlDuai crops impIicatioos for the shift from extcnsiYdy managed land to gn:aJcr rdiance 00 annual crops Land use in the El Pita! watershed and the associated increase in erosion hazard changed dramatically from 1968 to 1996. From (Figure 7). Wbtu planning land uses for a fium of 1968 to 1987, the forested, mixed crops, and any size, a &miJy provides for its subsisrmce mixed raogeIpasture areas in the El Pita! needs first and thea produces CnllllClciaI crops

II 1400

'C' 1200 ·F..... 1 a Rangeland ~"""'1aI Crope I 800 • AMualCrope 6 .~ UI 600 &l 400 I 200 ~ 0 0 10 20 30 40 50 SIqle(%)

Figure 6. Estimated annual soil loss associated with differences in slopes and cropping systems, EI Pital watershed, Nicaragua 100r------~ a Private ownershlp

• BenefICiaries 01 Agrarian Relorm •

•

Meal Faro Size (ha) Figure 7. Relationship between mean farm size and tbe proportion of tbe farm planted to annual crops, EI Pital watershed, Nicaragua

12 and other output for market. Therefore, the Conservation effort has been greater by BAR than smaller the fann the greater the proportion of land by private landowners (Figure 8) likely to be devoted to annual crops. Figure 7 shows that those operating small fanns plant a significantly \arger proportion of their fann to annual crops than do those with l;uge Beneficiaries of agr.uian reform (BAR) fanns. The data points plotted in Figure 7 are are more likely than private Iandowncrs to have from the \35 fanners interviewed in 1996. These small fanns focused on subsistence; acwcdingly, data show how, as a group, beneficiaries of they are likely to cultivate a \arger proportion of agrarian refonn are more subsistence-oriented their fanns to annual crops, C\'I:Il steepland sites, (and thus fann a greater proportion of annual than do private landowners. The focus of crops) than do private landowners. conservation programming on BAR is illustrated Since the late 1980s, the govennuent of by the contrast between their 1e\'CI of saIisfacIion Nicaragua has recognized that these demographics with tecbnical assistance they received, aepared of BAR make their fanns more prone to erosion, with that of private landowners (Figure 9). and thus increase their need for tecbnical Forty pelcent of pm'3te Iandov.ners have assistance with soil conservation. Non received DO tecbnical assistance ..;th soil governmental organizations have also targeted conservation at all, wbereas 40% of BAR several conservation projects to BAR. Due to the considered the tecbnical assistance ..tuch they conunittee structures associated with fann received to be excelIent. The pc::n:eutage of cooperatives, organizing conservation initiatives fanners using each of eight (of nine) cOIlsenation for BAR is more streamlined, institutionaI\y and practices (all except live fmces) was bigbcr for organizationaI\y, than is outreach to private land BAR than for private Iandowncrs (Figure 10). owners.

land tenure - ___II"" _ --.. .. _01

J" I

Figure 8. Mean Dumber of c:oasenation practices applied per farm, c:omparinc priYaIr IaIIdowDe1'5 with beDeIidaries of agrarian reform, EI PitaJ -tasbed, Nicarapa

\3 Land tenure

• Private ownership

• Beneficiaries of agrarian reform

None Poor Medium Good El«:ellent

Quality a Ca1ser.Bion TeclTicai Assis!a1ce as Assessed by F""""",

Figure 9. Level of satisfaction with technical assistance with soil and water conservation, comparing private landowners with beneficiaries of agrarian reform, El Pital watershed, Nicaragua

Land tenure

• Private ownership

• Beneficiaries of agrarian rafonn

I.MI tIage practices I11I'U8 catrd baniars Type of Soil and Water Conservation Practice

Figure 10. Types of soil and water conservation practices used in El Pital watershed, Nicaragua, comparing private landowners with beneficiaries of agrarian reform 14 Imerviews with faImers in 1996 suggest Faxm tjpmlics laid to meet their SIJbsisrmce fOod that both private Jaruiov,ners and BAR have a high needs bcfon: pmdocing crops fur (.MiijiC,ci,d level of a\liar!!i;!;; of the erosion hazard markets. Accotdingly, from 1968 to 1996, the associated with intensive rotations of annual pxedoxuin.lnt land use in the B Pita! watexshcd crops. 80th BAR and private 1andowucrs became annuaJ crops. More small farms means understand how planting pcrezmial crops can more subsistaJcc.OOcntc uuppiDg ~-staDs. reduce erosion, particularly on stecplands. Inc:n:ased cultivation of annuaJ wops is the main When asked about their loug-tcrm hopes, factor driving increasing erosion hazard, many fanners discussed plans to plam more fruit particularly on stecplands. trees. Private landowners and BA.~ perceived Soil conservation (Jrogxaxm 1aJgeIed ax severa1 obstacles to their personal in,,-estments in agrarian reform communities ha~'e been soil conservation and in their shift to a greater successful in reducing erosion hazard. As emphasis on perennia1 crops: lack of secure title, demonstrated by the n:suIts of this study, lack of access to credit, and tear of land gcogxaphic infuxmation ~'SfCmS (GIS), ..iIich distribution. For BAR in particu1ar, concern that enable simul1ancous analysis of~"SicaI and th: govex1D1ICilt would inb:rveuc to depress crop land tenure patterns, can aid in land use plaxming prices if production were to increase was to target where soil conservation efforts an: Iikdy considered the most significant barrier to making to yield the highest n:tum on ixMst.. ..m, public modifications in cropping patterns and to long andpm1!te. texm conservation investment. StraIegic inveslment in soil consexvaxion requires dialogue and coopexation betwew public POLICY IMPLICATIONS policy makers, beueficiaries of agxarian reform, and private landowners. These maps Significant land use change occurred in descnDing changes in estimated annua1 soil the B Pita! watexshed, Nicaxagua, from 1968 to losses associated with changing land use 1996. Agxarian reform, inhe:ritance customs, and patterns provide a statting place for their population growth have been instruxneoral in dialogue and their consideration ofinvestment promoting an increase in the mxmber of small and policy options. farms.

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