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elated over slightly longer distances than high silt contents. High sand values arespatially dependent over long distances of up to 4.4 km, whereas low sand contentschange rapidly over short distances (Table 5).Our results are thus not consistent with the general belief that soils of the KoratPlateau are universally coarse-textured and infertile. The SIK map assigns much land(25%) to soil texture class three (loam and heavier). A loamy soil is expected to besuitable for rice production. The reliance on soil maps may have contributed to thelong-held views about soil texture in northeast Thailand. In reality, soil texture in thisregion varies over short distances and the soil maps do not depict these changes.Colluvio-alluvial processes over short distances and in situ soil development are asimportant factors for the distribution of soils in northeast Thailand as is the graduallychanging Quaternary alluvial sedimentation.Conclusions1. Soil maps at scales of 1:100,000 to 1:125,000 highlight soil trends in theregion but don’t depict much of the agronomically important spatial variabilityand cannot be used for land resource assessment. Agronomic interpretationsshould be based on maps generated by detailed soil surveys or oncombining field data with existing information to produce refined thematicmaps with relevant spatial resolution.2. The UFFC that is based on local knowledge captures much of the variationin soil properties and does provide a basis for land resource assessment. Itsapplicability, however, excludes some soil properties (see RV c values) andlittle variation of pH, EC, Bray-II P, K, and Na is accounted for. Variation ofmore stable soil properties characterizing the inherent soil potential (texture,organic carbon, CEC) and Ca and Mg of the base complex can be assessedsufficiently.3. Although the average values of soil fertility indicators are low, their rangeand spatial distribution, in conjunction with soil development processes, confirminformation by farmers that soil fertility levels are sufficient for rainfedrice production in a large proportion of the land.4. The soft information used here is readily available in many regions or doesnot cost much to obtain. Therefore, instead of concentrating on additionalsampling with greater density, SIK provides an interesting cheap alternativefor updating or upgrading soil maps and describing spatial soil variability.5. Integration of hard and soft information revealed visually that colluvio-alluvialprocesses act over short distances and in situ soil development is likely.Large-scale variation, as suggested by the variograms and maps, is not consistentwith the widely held belief that Quaternary alluvial sedimentationwas the sole process responsible for the distribution of soils in the region.6. Geostatistical indicator approaches offer a suite of tools for characterizingand mapping soil variability in the rainfed rice lands, including variographyPerception, understanding, and mapping of soil variability . . . 93
and the possibility to generate quantile maps or maps that exceed specifiedthresholds.7. The results presented indicate the need for software that implements the SIKand other relevant algorithms in a standardized and user-friendly mode.ReferencesBeckett PHT, Webster R. 1971. Soil variability: a review. Soils Fert. 34:1-15.Black CA. 1965. Methods of soil analysis. Madison, Wis. (USA): American Society ofAgronomy.Bray RH, Kurtz LT. 1945. Determination of total, organic, and available forms of phosphorusin soils. Soil Sci. 59:39-45.Brus DJ, De Gruijter JJ, Breeuwsma A. 1992. Strategies for updating soil survey information:a case study to estimate phosphate sorption characteristics. J. Soil Sci. 43:567-581.Changprai C, Chotimon A, Thunduan V, Thipsuwan C, Lepananontha J, Kittiyarak S. 1971.Detailed reconnaissance soil map of Ubon Ratchathani Province. Bangkok (Thailand):Department of Land Development.Craig IA. 1988. Agronomic, economic and socially sustainable strategies for soil fertility managementin northeast Thailand. In: Chareonwatana T, Rambo AT, editors. Sustainablerural development in Asia. Fourth SUAN Regional Symposium on Agroecosystem Research.Khon Kaen (Thailand): Farming Systems Research Project and Southeast AsianUniversities Agroecosystem Network. p 153-165.Davis JG, Hossner LR, Wilding LP, Manu A. 1995. Variability of soil chemical properties intwo sandy, dunal soils of Niger. Soil Sci. 159:321-330.Dobermann A, White P. 1999. Strategies for nutrient management in irrigated and rainfed lowlandrice systems. Nutr. Cycl. Agroecosyst. 53:1-18.Goovaerts P. 1997. Geostatistics for natural resources evaluation. New York (USA): OxfordUniversity Press.Grandstaff TB. 1988. Environment and economic diversity in Northeast Thailand. In:Chareonwatana T, Rambo AT, editors. Sustainable rural development in Asia. FourthSUAN Regional Symposium on Agroecosystem Research. Khon Kaen (Thailand): FarmingSystems Research Project and Southeast Asian Universities Agroecosystem Network.p 11-22.Kubiniok J. 1990. Relief- und Bodengeneration auf dem Khorat-Plateau (NE-Thailand).Zeitschrift für Geomorphol. 34:149-164.Löffler E. 1984. Quarternary geomorphological development of the Lower Mun River Basin,North East Thailand. Catena 11:321-330.Mackill DJ, Coffman WR, Garrity DP. 1996. Rainfed lowland rice improvement. Manila (Philippines):International Rice Research Institute. 242 p.Michael P. 1982. The landforms of Thailand: ideas about their genesis and influence on soilproperty distribution. In: Nutalaya P, Karasudhi P, Tanasuthipitak T, Kheoruenromme I,Sudhiprakarn A, editors. First International Symposium on Soil, Geology and Landforms:Impact on Land Use Planning in Developing Countries. Bangkok (Thailand):Association of Geoscientists for International Development. p C10.1-C10.14.Mitsuchi M, Wichaidit P, Jeungnijnirund S. 1989. Soils of the Northeast Plateau, Thailand.Tsukuba (Japan): Tropical Agriculture Research Center.94 Oberthür and Kam
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The International Rice Research Ins
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Monitoring rainfed and irrigated ri
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ForewordRainfed rice areas are asso
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AcknowledgmentsIRRI is most gratefu
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2 Singh et al
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development, for example, provision
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subecosystems were recognized withi
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Table 3. Methods commonly used in e
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Table 4 continued.Scale of analysis
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Table 4 continued.Scale of analysis
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This included standard countrywide
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deepwater rice ecosystems. The rese
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Table 5 continued.Main MethodologyC
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Table 5 continued.Main MethodologyC
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Table 5 continued.Main Scale presen
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levels of involvement. For example,
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●●●ecosystem classifications
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Conclusionsclearly that they are di
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IRRI (International Rice Research I
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Widawsky DA, O’Toole JC. 1990. Pr
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Rice is the staple food crop for mo
Page 44 and 45: first working group to identify the
Page 46 and 47: TropicsSubtropicsTemperateSummer/wi
Page 48 and 49: ferred it for wide adoption by farm
Page 50 and 51: ing, remote sensing, and computing
Page 52 and 53: ice environments will be needed to
Page 54 and 55: Insects and diseasesInsects and dis
Page 56 and 57: The completeness of characterizatio
Page 58 and 59: Table 7. Levels and scales for agro
Page 60 and 61: Jamin JY, Andriesse W. 1993. Discus
Page 62 and 63: Tools and methodologiesfor biophysi
Page 64 and 65: Effect of climate, agrohydrology,an
Page 66 and 67: to water deficit because the crop
Page 68 and 69: for different periods of the year:
Page 70 and 71: depth scenarios (shallow, medium, a
Page 72 and 73: Water table depth (cm)500Shallow wa
Page 74 and 75: Simulated yield (kg ha -1 )6,0005,0
Page 76 and 77: Perception, understanding,and mappi
Page 78 and 79: and rice yield at regional or more
Page 80 and 81: SubareaSampling sites:GridTransectR
Page 82 and 83: was approximately 2,000 m with a to
Page 84 and 85: kg -1 in 50% of the topsoil and sub
Page 86 and 87: Table 3. Class medians were calcula
Page 88 and 89: Hard point dataClay, silt, sandHard
Page 90 and 91: A. Silt (%) B. 0.5 ccdfC. 0.2 ccdf
Page 92 and 93: In summary, the chosen geostatistic
Page 96 and 97: Miura K. 1990. Genetic features of
Page 98 and 99: Rainfed lowland rice, growing with
Page 100 and 101: tively. In 1993, following dry till
Page 102 and 103: Rainfall (mm)Water table depth (cm)
Page 104 and 105: Saturated hydraulic conductivity (c
Page 106 and 107: in the uncompacted C0 plots (6.7 wk
Page 108 and 109: Clay classified≤ 2% 50 ha (2% but
Page 110 and 111: NotesAuthors’ addresses: D. Harnp
Page 112 and 113: target area of a breeding program.
Page 114 and 115: which is calculated from the estima
Page 116 and 117: hence grain yield. The three major
Page 118 and 119: ainfall data for each location. Mea
Page 120 and 121: such as 1980 and 1996, yield was hi
Page 122 and 123: Table 1 shows the results of the se
Page 124 and 125: Grain yield (t ha -1 )3UBN 19942103
Page 126 and 127: decreased with the use of old seedl
Page 128 and 129: The use of five genotypes with diff
Page 130 and 131: Mackill DJ, Coffman WR, Garrity DP.
Page 132 and 133: In rainfed agriculture, crop perfor
Page 134 and 135: GrainSite Year Code Group yield San
Page 136 and 137: Criteria considered for selecting r
Page 138 and 139: Table 1. Characteristics of the ref
Page 140 and 141: equired as the quality of the repro
Page 142 and 143: Cooper M, Rajatasereekul S, Immark
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144 Amien and Las
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As Indonesia’s staple food, rice
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Soil and climate of rainfed lowland
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isky when the crop is planted late.
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The decrease in harvested area only
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than in tidal swamp rice, for which
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Monitoring rainfed and irrigated ri
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and, indirectly, methane emission f
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Radar backscatter (dB)-7ERS windsca
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ERS SAR imageseries2. RSpreprocessi
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Fig. 6. Supervised classification o
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ConclusionsMonitoring of rice crops
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Characterizing soil phosphorusand p
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Table 1. Area and distribution of s
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Table 2. Lowland area (ha) classifi
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Fig. 1. Extractable soil P map (25%
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Characterizing soil phosphorus and
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Table 4. Recommendations for P appl
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Fig. 4. Extractable soil K map of t
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Fig. 5. Extractable soil K map of t
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● acidic pH (< 6)● low organic
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trials, K recommendations for uplan
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O’Brien DT, Blair G, Lefroy R. 19
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Planning and managing rice farmingt
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lowlands is submergence-prone. Ther
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situations and the allocation of re
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estimation of drought were determin
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Table 2. Effect of date of sowing,
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from October to February and a summ
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Table 3. Promising areas for ground
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1. There are possibilities of growi
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mmmm450350250150ASoil moisture useS
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Table 9. Yield a of preflood ahu (a
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Grain yield (t ha -1 )6Farmers’ l
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ReferencesIRRI (International Rice
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network (Sastry 1976). Temperature
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Temperature (°C) and solar radiati
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Table 1. Characterization of rainfa
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in eastern Uttar Pradesh under norm
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fluctuations/variations in rainfall
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the desirable rainfall period at 50
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The radiation values range from les
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not affect the growth and developme
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Agrohydrologic and drought riskanal
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Analytical procedureThe nature and
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late because of low rainfall at the
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Probability (%)10080604020Vegetativ
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15 August), which may happen twice
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texture), then once in two years (5
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Characterizing biotic stresses
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Characterizing biotic constraintsto
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included in these studies. Later st
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Average number of insects per sweep
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Table 2. Categorization of weed and
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Table 5. Properties of individual c
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ResultsRelations among pests and cr
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Start hereInterview farmers todocum
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Table 10. Information used to prior
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Interpreting the results of indepen
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level. Again, we augment our databa
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NotesAuthors’ address: Cambodia-I
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in soil nutritional status, especia
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flora. The range in elevation acros
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Table 1. Soil characteristics of th
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Table 3. Weed species recorded and
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Proportional abundance (log scale)%
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1.0Echi_colCype_iriMoll_penLind_spp
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+3.0Echi_cruMars_creEcli_albLept_ch
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indicates the need to deploy broad-
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ReferencesBangun P, Pane H, Jatmiko
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Socioeconomic characterization
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The role of characterizationin ex a
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ApproachThe following steps were ta
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PriceDS 0S 1P 0P 1dS 0S 1acbD0 Q 0Q
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Table 1. Ex ante assessment of rese
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Table 2 continued.Ranked byResearch
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Table 3. Research resource allocati
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NotesAuthors’ address: National C
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In addition to the unavailability o
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Socioeconomic constraintsFarm sizeF
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found that a higher rural labor sup
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Table 3. Rice area under HYVs from
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Rice varieties in farmers’ fields
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Table 9. Constraints for low adopti
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vehicle for realizing the untapped
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Parthasarathy G, Prasad DS. 1978. R
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Appendix. Agroclimatic zones of Bih
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such that losses are reduced during
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P = 0.5 R [a 2 C r2+ 2 a (1 - a) g
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and Itgaon, however, the plot-level
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espectively, to farmers’ income.
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Factors determining the adoption of
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mining whether or not modern variet
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irrigation schemes in the study are
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Using gender analysis in characteri
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lytical tool used to identify or di
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However, household members have cer
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Table 1. Village characteristics of
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taking care of dairy cattle. On the
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The biophysical environmentThe perf
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Table 3. Seasonal calendar and gend
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Table 4. Crops grown during the kha
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Table 7. Labor input (person-days h
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Table 8. Labor input (person-days h
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Table 10. Cost and returns of rice
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Gender roles in animal husbandryWhe
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farm activities, 25% in nonfarm act
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for rice but also for cash crops su
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Table 15. Access to agricultural in
Page 362 and 363:
Hossain M. 1995. Recent development
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Agricultural commercializationand l
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Conceptual frameworkPopulation pres
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tional average of 18% 1 , and most
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The Dzao live in medium-altitude ar
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Table 1. Selected districts and com
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Table 2. General characteristics of
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markets for their food needs. With
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ther “extensification” in the u
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the productivity of lowland rice ca
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Boserup E. 1981. Population and tec
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Economics of intensive rainfed lowl
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Area (ha)50,00040,000Irrigated30,00
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The economic characterization and i
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Table 1. Rice varieties planted (19
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Table 4. Yield and input use of maj
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TFP, output and input indices200160
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Lynam JK, Herdt RW. 1989. Sense and
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406 Garcia et al
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Increased rice production had alway
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Table 1. Total rice area, average y
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use of water by avoiding seedbed pr
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water often brought with it a varie
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Table 4. Distribution of farm house
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Soil types found in the villages we
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Table 10. Ownership of agricultural
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in a group) at the rate of $60 per
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Table 13. Pattern of loan use (% of
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Labor and employmentTable 16 presen
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Table 17. Incidence of child labor
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Cumulative proportion of income1.04
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Table 21. Cost and return analysis
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Table 22. Estimated rice yield and
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were often burned for disease contr
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landless population reaching 50-60%
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Integration of biophysical andsocio
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opinion regarding what socioeconomi
Page 436 and 437:
1995-96 Rice production (t)TvRd6Rd1
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Farm-gate price of agricultural goo
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ming the distance of all line segme
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Description of the study areaWe com
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Table 1 continued.Variable Unit1994
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CambodiaFig. 4. Main transport rout
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Table 2. Accessibility indicators f
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ice and the model is applied to exp
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Table 3. Summary of estimates of la
Page 454 and 455:
estimation of a system of multinomi
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The availability of low-saline irri
Page 458 and 459:
Table 5. Simulation of effects of i
Page 460 and 461:
NotesAuthors’ address: Social Sci
Page 462 and 463:
that they synthesize fragmented agr
Page 464 and 465:
Framework for exploratory and predi
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and quantify the spatial distributi
Page 468 and 469:
Seventeen different agricultural pr
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self-sufficiency in rice production
Page 472 and 473:
al warming since maintaining or cre
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eturns to purchased inputs due to u
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Francisco SR, Navarrete Jr. RL, Dim
Page 478:
Wade L. 1998. Nutrient research on
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