BETTER LAND HUSBANDRY
CONTENTS 1 INTRODUCTION TO BETTER LAND HUSBANDRY 1 1 1 LAND AND SOIL DEGRADATION 1 1 2 SOIL CONSERVATION TECHNOLOGIES 6 1 3 BETTER LAND HUSBANDRY APPROACH 10 1 4 WINNING THE DEBATE 18 2 SOCIAL AND ECONOMIC COMPONENTS OF BETTER LAND HUSBANDRY 20 2 1 CONVENTIONAL SOIL CONSERVATION APPROACH 20 2 2 FARMERS REALITIES 26 2 3 PUTTING FARMERS FIRST 35 2 4 UNLOCKING THE COMPLEXITY OF FARMERS REALITIES 42 2 5 FARMERS PRIORITY NEEDS 54 2 6 OBSTACLES TO BETTER LAND MANAGEMENT 62 2 7 FARMERS RELATIONSHIP WITH OUTSIDERS 72 2 8 TAPPING INTO FARMERS RESOURCEFULNESS 76 3 AGRO ECOLOGICAL COMPONENTS OF BETTER LAND HUSBANDRY 81 3 1 QUESTIONING THE SOIL CONSERVATION APPROACH 81 3 2 SOIL EROSION PROCESSES 82 3 3 ARE THE DATA RELIABLE 87 3 4 TESTING THE SOIL CONSERVATION APPROACH 95 3 5 MEASURING RAINFALL 116 3 6 IMPACTS OF CONVENTIONAL AGRICULTURE 120 3 7 EFFECTIVENESS OF SOIL CONSERVATION TECHNOLOGIES 127 3 8 SOIL CONSERVATION AND SITE VARIABILITY 135 3 9 TIME FOR A RETHINK 138 4 BETTER LAND HUSBANDRY A NEW PARADIGM 140 4 1 SOIL CONSERVATION VERSUS BETTER LAND HUSBANDRY 140 4 2 NEW PERSPECTIVES ON SOIL EROSION AND LAND DEGRADATION 141 4 3 IMPORTANCE OF SOIL QUALITY 149 4 4 MAINTAINING AND IMPROVING SOIL QUALITY 162 4 5 LESSONS FOR OUTSIDERS 177 4 6 BETTER LAND HUSBANDRY WHY HAS IT TAKEN SO LONG 181 5 BETTER LAND HUSBANDRY IN PRACTICE 185 5 1 INTRODUCTION TO CASE STUDIES 185 5 2 ZERO TILLAGE IN SOUTH AMERICA 185 5 3 SOIL COVER IN HONDURAS 192 5 4 FARMER PARTICIPATION IN HONDURAS 195 5 5 SOIL MOISTURE AND YIELDS IN AFRICA 205 5 6 HURRICANE MITCH FROM SOIL EROSION TO LANDSLIDES 210 6 BETTER LAND HUSBANDRY AND POLICY 218 6 1 A NEW APPROACH TO LAND MANAGEMENT 218 6 2 FUTURE OF SMALLHOLDER FARMING 219 6 3 A NEW PROFESSIONALISM 222 6 4 FROM PRODUCTION TO MARKETS 228 6 5 BROADENING THE POLICY AGENDA 233 6 6 BETTER LAND HUSBANDRY AND FUTURE RESEARCH 238 1 INTRODUCTION TO BETTER LAND HUSBANDRY HUMAN INDUCED AGRICULTURAL LAND DEGRADATION IS WIDESPREAD IN IRRIGATED AND RAINFED LAND AND IN BOTH TROPICAL AND TEMPERATE ZONES LAND DEGRADATION REPRESENTS A CHALLENGE TO THE SUSTAINABILITY IN ALL REGIONS EVEN THOSE OF LOW POPULATION DENSITIES SHAXSON AND BARBER 2003 2 1 1 LAND AND SOIL DEGRADATION SINCE 1700 AND AS POPULATIONS HAVE INCREASED THE CULTIVATED AREA OF THE EARTH HAS INCREASED BY NEARLY 6 FOLD PIMENTEL ET AL 1995 BY THE YEAR 2020 THE WORLD WILL HAVE AROUND 7 7 BILLION PEOPLE OF WHOM 84 PERCENT WILL BE IN DEVELOPING COUNTRIES SCHERR 1999 31 THESE PEOPLE WILL NEED TO BE FED AND AS POPULATIONS GROW AND INEQUALITIES IN LAND DISTRIBUTION CONTINUE THE AMOUNT OF CULTIVABLE LAND PER CAPITA WILL DECLINE IF THE WORLD S PRESENTLY CULTIVATED ARABLE LAND AREA IS MAINTAINED AT ABOUT 1 45 BILLION HECTARES HA THE PER CAPITA ARABLE LAND WILL FALL FROM APPROXIMATELY 0 25 HA TO 0 15 BY 2050 LAL 1991 ONE OF THE CHALLENGES IN THE TROPICS AND SUBTROPICS IS THEREFORE TO INTEN SIFY THE OUTPUT FROM THE LAND WITHOUT DESTROYING THE LAND RESOURCE SOIL WATER AND LAND UPON WHICH IT ALL DEPENDS SHAXSON 1993 DUMANSKI ET AL 1998 108 PIERI ET AL 1995 1 EL ASHRY 1988 IN THE FRONT LINE OF THIS STRUGGLE ARE STEEPLANDS THESE CAN BE DEFINED AS LAND WITH AN AVERAGE SLOPE OF MORE THAN 20 PERCENT IN THESE AREAS ECONOMICALLY DISADVANTAGED FARMERS ARE BRING ING FRAGILE AND ERODIBLE LANDS INTO CULTIVATION STOCKING 1995 IT IS AN IM MENSE CHALLENGE AND OUR ACHIEVEMENT TO DATE HAS NOT BEEN PARTICULARLY EN COURAGING THERE ARE HOWEVER PARTS OF THE WORLD WHERE PEOPLES HAVE LIVED SUSTAINABLY IN MOUNTAINOUS REGIONS FOR CENTURIES AND WHERE THEY HAVE DEVEL OPED AGRICULTURAL PRACTICES THAT ARE WELL SUITED TO THE REGION EXAMPLES IN CLUDE COMMUNITIES LIVING IN THE ANDES IN SOUTH AMERICA IN GENERAL THOUGH THE RESULT OF ATTEMPTS TO INCREASE PRODUCTION IN STEEPLANDS HAS OFTEN BEEN SOIL AND LAND DEGRADATION LAND DEGRADATION IS A COMPOSITE TERM FOR THE AGGREGATE DIMINUTION OF THE PRODUCTIVE POTENTIAL OF THE LAND INCLUDING ITS MAJOR USES RAINFED ARABLE IRRIGATED RANGELAND FOR ESTRY ITS FARMING SYSTEMS E G SMALLHOLDER SUBSISTENCE AND ITS VALUE AS AN ECONOMIC RESOURCE SOIL DEGRADATION WHICH INCLUDES SOIL EROSION IS ANY PROC ESS THAT REDUCES THE CURRENT AND OR FUTURE PRODUCTIVITY OF SOILS SEE BOX 1 1 1 BOX 1 1 SOIL DEGRADATION TWO CATEGORIES OF SOIL DEGRADATION PROCESSES ARE RECOGNISED THE FIRST CATEGORY IS SOIL EROSION DEFINED AS THE DISPLACEMENT OF SOIL MATERIAL EITHER BY WATER OR WIND SOIL EROSION IS ONE OF THE MAIN PROCESSES OF SOIL DEGRADATION AND THE BULK OF RESEARCH AND PRACTICAL ATTEMPTS TO ALLEVIATE THE PROBLEM OF LAND DEGRADATION HAS BEEN DIRECTED AT CONTROLLING SOIL LOSS EROSION OF EXPOSED SOIL LEADS TO THE LOSS OF FINE PARTICLES RICH IN ORGANIC MATTER AND BASIC PLANT NUTRIENTS SUCH AS NITROGEN PHOSPHOROUS POTASSIUM AND CALCIUM WHICH ARE ATTACHED TO THE ERODED SEDIMENTS AND WHICH ARE ESSENTIAL FOR CROP PRODUCTION NORMAN AND DOUGLAS 1994 5 LAVELLE ET AL 1992 EROSION DECREASES SOIL S WATER HOLDING CAPACITY REDUCES EFFECTIVE ROOTING DEPTH AND PLANT AVAILABLE WATER RESERVES EXPOSES RELATIVELY INFERTILE SUBSOIL AND ADVERSELY AFFECTS PLANT GROWTH AND VIGOUR EROSION IS A SERIOUS PROBLEM AND STOCKING 1995 ESTIMATES THAT SINCE 1945 1 2 BILLION HA AN AREA ROUGHLY THE SIZE OF CHINA AND INDIA COMBINED HAVE BEEN ERODED TO THE POINT WHERE THEIR ORIGINAL BIOTIC FUNCTIONS ARE IMPAIRED THE SECOND GROUP DEALS WITH SOIL DETERIORATION IN SITU THIS CAN INVOLVE BIOLOGICAL CHEMICAL OR PHYSICAL SOIL DEGRADATION PROCESSES THAT LEAD TO A DECLINE IN SOIL QUALITY HURNI ET AL 1996 11 THESE PROCESSES INCLUDE COMPACTION AND REDUCED WATER HOLDING CAPACITY IMPAIRMENT OR ELIMINATION OF ONE OR MORE IMPORTANT POPULATIONS OF MICROORGANISMS REDUCTION IN SOIL ORGANIC MATTER REDUCED STRUCTURAL STABILITY OF SOIL CRUMB STRUCTURE WHICH BECOMES MORE VULNERABLE TO COLLAPSE ON WETTING OR WHEN SUBJECTED TO MECHANICAL STRESS EXCESSIVE LEACHING OF CATIONS IN SOILS WITH LOW ACTIVITY WHICH LEADS TO A DECLINE IN SOIL PH AND A REDUCTION IN BASE SATURATION SOIL DEGRADATION IS A MAJOR COMPONENT OF LAND DEGRADATION AND HUMAN INDUCED SOIL DEGRADATION WORLDWIDE HAS AFFECTED 1 966 MILLION HA THIS REPRESENTS 15 PERCENT OF THE TOTAL LAND AREA OR 38 PERCENT OF AGRICULTURAL LAND WORLDWIDE FURTHERMORE IT HAS BEEN SUGGESTED THAT WORLDWIDE APPROXIMATELY 12 106 HA OF ARABLE LAND ARE DESTROYED AND ABANDONED ANNUALLY BECAUSE OF UNSUSTAINABLE FARMING PRACTICES PIMENTEL ET AL 1995 THE MAJOR CAUSES OF BOTH LAND AND SOIL DEGRADATION ARE POOR LAND HUSBANDRY AND UNSUSTAINABLE AGRICULTURE PRACTICE NATURAL RATES OF SUBSOIL FORMATION IN THE TROPICS BY THE SLOW PROCESS OF ROCK WEATHERING ARE ESTIMATED TO BE IN THE REGION OF 0 5 1 T HA 1 YR 1 STOCKING 1995 SINCE THIS IS APPROXIMATELY EQUIVALENT TO NATURAL RATES OF SOIL EROSION ALL AGRICULTURAL AND LAND USE SYSTEMS ARE THEORETICALLY UNSUSTAINABLE BECAUSE ALMOST ANY DISTURBANCE WILL CAUSE AN INCREASE IN SOIL LOSS ABOVE THE NATURAL RATE OF SUBSOIL FORMATION 2 HOWEVER SOIL FORMATION IS A TWO WAY PROCESS AND IS EQUALLY DUE TO THE ADDITION OF ORGANIC MATTER THROUGH THE DECAY OF ROOTS IN THE SOIL THROUGH THE CHURNING ACTIONS OF SOIL ORGANISMS INCLUDING EARTHWORMS AND THE ACCUMULATION OF LITTER AT THE SOIL SURFACE THIS IS WHY AS WE WILL SEE IN CHAPTER 4 THE ADDITION OF ORGANIC MATTER HUMIFICATION AND TILLAGE CAN LEAD TO THE FORMATION OF SOILS FROM THE TOP DOWNWARDS SHAXSON 1999 9 HUMAN ACTIVITIES OR FACTORS RESPONSIBLE FOR SOIL AND LAND DEGRADATION INCLUDE DEFORESTATION CULTIVATION OF MARGINAL LANDS EXCESSIVE AND INDISCRIMINATE USE OF CHEMICALS AND EXCESSIVE GRAZING WITH HIGH STOCKING RATES LAL AND STEWART 1990 SOIL AND LAND DEGRADATION ARE OFTEN GREATER PROBLEMS IN MANY DEVELOPING COUNTRIES BECAUSE IN THE TROPICS SOILS COMMONLY HAVE INHERENT FERTILITY PROBLEMS TYPICALLY THEY ARE LOW IN NUTRIENTS AND ORGANIC MATTER BECAUSE THE HIGHER TEMPERATURES FAVOUR THE MORE RAPID DECOMPOSITION OF ORGANIC RESIDUES AND HAVE LOW WATER HOLDING CAPACITY DUE TO A COARSE TEXTURE AND LOW CLAY CONTENT DOUGLAS 1993 IN RECENT YEARS MANY SMALLHOLDER FARMERS HAVE BEEN DISPLACED FROM THEIR TRADITIONAL LANDS BY WAY OF VARIOUS KINDS OF PRESSURES SUCH AS INEQUALITIES IN ACCESS TO LAND POPULATION GROWTH AND THE EXPANSION IN AREA OF LARGE SCALE COMMERCIAL AGRICULTURE HAWKESWORTH AND GARCIA P REZ 2003 TADESSE AND BELAY 2004 MANY OF THESE SMALLHOLDER FARMERS HAVE TAKEN TO THE CULTIVATION OF EVER STEEPER HILLSIDES SEE BOX 1 2 AND PLATE 1 BOX 1 2 POLITICAL SOCIAL AND ECONOMIC DIMENSIONS TO SOIL AND LAND DEGRADATION THROUGHOUT THE WORLD CASH CROPS HAVE CLAIMED THE BETTER LANDS AND HAVING BEEN DISPLACED FROM THESE LANDS SMALLHOLDER FARMERS HAVE FEW ALTERNATIVES BUT TO CULTIVATE STEEP AND MARGINAL AREAS EL SWAIFY 1994 STONICH 1991 COUNTRIES SUCH AS HONDURAS IN CENTRAL AMERICA ARE NO EXCEPTION TO THIS RULE IN HONDURAS 90 PERCENT OF THE LAND DESIGNATED AS AGRICULTURAL IS IN THE HANDS OF 10 PERCENT OF THE PRODUCERS SECRETAR A DE COORDINACI N PLANIFICACI N Y PRESUPUESTO 1989 FURTHERMORE 2 8 M HA IS CLASSIFIED AS AGRICULTURAL LAND 25 PERCENT OF THE LAND AREA BUT ALMOST 4 0 M HA ARE FARMED THE DIFFERENCE OF 1 2 M HA IS LARGELY MADE UP BY APPROPRIATION OF HILLSIDES THE INEQUITABLE DISTRIBUTION OF LAND IN HONDURAS THAT FORCES FARMERS ONTO STEEPLANDS INCREASED AFTER THE SECOND WORLD WAR COMMENSURATE WITH THE GROWTH OF AGRICULTURAL EXPORT CROPS AND A HIGH POPULATION GROWTH RATE 3 2 PERCENT PER ANNUM ACCORDING TO LEONARD 1987 38 IN THE 1950S AND 1960S PARTS OF HONDURAS WERE FOR THE FIRST TIME DRAWN INTIMATELY INTO NATIONAL AND INTERNATIONAL MARKETS THERE WAS A GROWTH IN NON TRADITIONAL AGRICULTURAL EXPORTS SUCH AS COTTON SUGAR AND BEEF STONICH 1995 STONICH AND DEWALT 1989 DURHAM 1979 117 3