Staff Publications

Staff Publications

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    'Staff publications' is the digital repository of Wageningen University & Research

    'Staff publications' contains references to publications authored by Wageningen University staff from 1976 onward.

    Publications authored by the staff of the Research Institutes are available from 1995 onwards.

    Full text documents are added when available. The database is updated daily and currently holds about 240,000 items, of which 72,000 in open access.

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    How small is beautiful? : food self-sufficiency and land gap analysis of smallholders in humid and semi-arid sub Saharan Africa
    Hengsdijk, H. ; Franke, A.C. ; Wijk, M.T. van; Giller, K.E. - \ 2014
    Wageningen : Plant Research International, Business Unit Agrosystems Research (Report / Plant Research 562) - 46
    zelfvoorziening - kleine landbouwbedrijven - voedsel - landbouwhuishoudens - huishoudens - gewasproductie - humide klimaatzones - semi-aride klimaatzones - afrika ten zuiden van de sahara - self sufficiency - small farms - food - agricultural households - households - crop production - humid zones - semiarid zones - africa south of sahara
    Soil macrofauna community structure along a gradient of land use intensification in the humid forest zone of southern Cameroon.
    Madong à Birang, - \ 2004
    Wageningen University. Promotor(en): Lijbert Brussaard, co-promotor(en): W.A.M. Didden; S. Hauser. - Wageningen : S.n. - ISBN 9789085040316 - 200
    bodemfauna - bodeminvertebraten - aardwormen - formicidae - isoptera - zwerflandbouw - landgebruik - bossen - humide klimaatzones - kameroen - macrofauna - soil fauna - soil invertebrates - earthworms - formicidae - isoptera - shifting cultivation - land use - forests - humid zones - cameroon - macrofauna
    The impact of land use systems on soil macrofauna community structures is described as well as their relationships with the vegetation and soil parameters in the humid forest zone of southernCameroon. 36 Earthworm species were found. A completely different earthworm assemblage was found at high LUI while low and medium LUI blocks had species in common in the various functional groups. Earthworm surface casting decreased when fallow plots were converted to cultivated fields. This reduction depended on the type of fallow. 223 Termite species were recorded.There was no significant effect of LUI but in contrast, a strong effect of LUS on termite species richness and abundance. 80 Ant species were found. LUI and LUS had striking effects on ant communities with highest richness in the low LUI block. Ant species assemblages were location specific.Soil macrofaunal species richness was more responsive to soil and vegetation parameters than macrofaunal abundances.The knowledge gathered on the present state of earthworm, termite and ant communities and the effects of land use change on these macrofauna in southernCameroonconstitutes the baseline information necessary for the design and /or implementation of measures of conservation in which farmers should play a pivotal role.
    Slash and burn agriculture in the humid forest zone of southern Cameroon
    Kanmegne, J. - \ 2004
    Wageningen University. Promotor(en): Lijbert Brussaard; E.M.A. Smaling. - Wageningen : s.n. - ISBN 9789051130706 - 184
    inga edulis - zwerflandbouw - gewasopbrengst - wormhoopjes - landgebruik - verbeterde braak - ontbossing - voedingsstoffen - humide klimaatzones - bossen - kameroen - inga edulis - shifting cultivation - crop yield - worm casts - land use - improved fallow - deforestation - nutrients - humid zones - forests - cameroon
    Keywords: crop yields, earthworm cast, Inga edulis , land use, nutrient flows, nutrient stocks, nutrient management, slash and burn

    A field study was conducted on acid soils in the humid forest zone of Southern Cameroon, to characterize the traditional slash-and-burn land uses, assess the major effects of land use change on soil nutrient stocks, flows, and soil biological quality, and to explore alternatives for sustainable land management. The typical land use chronosequence in the area after forest felling includes essep (cucumber-based), banana, and afup (groundnut/cassava-based), and is interrupted by short (after banana) and long (after afup) fallows. Moreover, farmers have cocoa farms where many shade trees are kept. Yield declines in farmers' fields were attributed to diseases and weed infestation (56%) and soil properties (44%).  Burning is practiced prior to essep, and prior to afup. It reduces the weed seed-bank, cleans the field and improves short-term soil fertility, but, together with changing land use, it strongly reduces standing biomass, carbon and nutrient stocks in the vegetation. The forest carbon stock decreased from 199 Mg.ha -1 to 102 Mg.ha -1 in essep , and to 64 Mg.ha -1 in banana farm. Nutrient stocks showed the same trend, but Chromolaena short fallow, that followed banana, recovered most of the P. The cocoa plantation had 53 % of the carbon stocks of the original forest. Soil carbon stock was less affected than vegetation stocks.Burning increased P, K, Ca and Mg available stocks in essep and afup . Lowest 'system' C and N occurred in afup , which is followed by a long fallow to restore soil fertility. The nutrient balance at farm level was strongly negative, i.e., -72.6 kg N, -4.8 kg P and -38.2 kg K ha -1 yr -1 , showing its 'no external input' character, where food and wood are derived from natural stocks. Major losseswere dueto burning, leaching and the non-recycling of farm residues. Only the cocoa farm had a positive nutrient balance: +9.6 kg N, +1.4 kg P and +7.6 kg K ha -1 .yr -1 , as burning is absent, leachingmodest,and deep capture by shade trees providing inputs to the productive system. Simple scenarios showed that recycling farm residues is able to redress the P and K balance, and avoiding burning could even turn the entire nutrient balance positive. Burning also negatively affected earthworm density and casting activities. Up to 95% loss in density was recorded, and casting activity was inhibited during 14 and 19 months in land use systems following afup and essep respectively. Inga fallow proved to favour rapid and intensive casting just as the forest ecosystem. Total cast production was: 5.9 Mg.ha -1 in afup , 3.2 Mg.ha -1 in forest and Inga , and 2.9 Mg.ha -1 in essep after two years, but although the casts were richer in nutrients than the topsoil, the nutrients recycled from casts alone were insufficient for sustained crop production.   Inga edulis was found to be a suitable planted fallow, providing several benefits to farmers and follow-up crops.   Inga fallows produce more biomass (between 44.5 and 62 Mg ha -1 ), and accumulate more C and N than natural fallow. Maize following Inga fallow yielded 800 to 2200 kg.ha -1, against a mere 200-400 kg.ha -1 after natural fallow.  Burning Inga residues gave ngon (cucumber) productionof 300 kg.ha -1 ,which is similar to yields obtained in essep following natural forest. Mulching instead of burning, however, only gave50 kg.ha -1. An innovative on-farm approach was used in the development and implementation of planted fallows, ensuring highadoption. Inga edulis planted fallow can play a leading role among strategies to fight the gradual process of land degradation in the land use chronosequence, providing wood and fruits, and mimicking the natural forest to a considerable extent.
    Occurrence of soil water repellency in arid and humid climates
    Jaramillo, D.F. ; Dekker, L.W. ; Ritsema, C.J. ; Hendrickx, J.M.H. - \ 2000
    Journal of Hydrology 231/232 (2000). - ISSN 0022-1694 - p. 105 - 111.
    bodemwater - hydratatie - afstoting - dehydratie - evaporatie - humide klimaatzones - soil water - hydration - repellency - dehydration - evaporation - humid zones
    Natuurlijke verjonging van beuk : een lichtingsproef op rijke holtpodzolgrond
    Oosterbaan, A. ; Hees, A.F.M. van - \ 1991
    Wageningen : De Dorschkamp (Rapport / De Dorschkamp Instituut voor Bosbouw en Groenbeheer nr. 636) - 34
    bosbouw - bomen - natuurlijke verjonging - kroondak - kroon - bodemtypen - humide klimaatzones - fagus sylvatica - forestry - trees - natural regeneration - canopy - crown - soil types - humid zones
    Een orienterende proef met maatregelen ter bevordering van natuurlijke verjonging van beukenopstanden op vochtige veldpodzolgronden
    Oosterbaan, A. - \ 1990
    Wageningen : De Dorschkamp (Rapport / "De Dorschkamp" Instituut voor Bosbouw en Groenbeheer nr. 583) - 16
    bosbouw - bomen - natuurlijke verjonging - grondvoorbereiding - bodemtypen - humide klimaatzones - fagus sylvatica - forestry - trees - natural regeneration - site preparation - soil types - humid zones
    Mechanized annual cropping on low fertility acid soils in the humid tropics. A case study of the Zanderij soils in Suriname.
    Janssen, B.H. ; Wienk, J.F. - \ 1990
    Wageningen : Agricultural University (Wageningen Agricultural University Papers 90-5) - ISBN 9789067541725 - 230
    grondbewerking - zaaibedbereiding - veldgewassen - akkerbouw - humide klimaatzones - tropen - suriname - tillage - seedbed preparation - field crops - arable farming - humid zones - tropics - suriname
    Changes in physical properties of young and old volcanic surface soils in Costa Rica after clearing of tropical rain forest.
    Spaans, E.J.A. ; Baltissen, G.A.M. ; Bouma, J. ; Miedema, R. ; Lansu, A.L.E. ; Schoonerbeek, D. ; Wielemaker, W.G. - \ 1989
    Hydrological Processes 3 (1989). - ISSN 0885-6087 - p. 383 - 392.
    vulkanische gronden - andepts - andosols - bosbouw - woeste grond - landgebruik - bossen - relaties - ontbossing - bebossing - bodemfysica - grondmechanica - humide klimaatzones - tropen - costa rica - volcanic soils - andepts - andosols - forestry - waste land - land use - forests - relationships - deforestation - afforestation - soil physics - soil mechanics - humid zones - tropics - costa rica
    Research on acid sulphate soils in the humid tropics : second mission report modelling component
    Ritsema, C.J. ; Bronswijk, J.J.B. - \ 1988
    Wageningen : ICW (Nota / Instituut voor Cultuurtechniek en Waterhuishouding 1882) - 11
    zure gronden - kattekleigronden - humide klimaatzones - tropen - theorie - ontwerp - acid soils - acid sulfate soils - humid zones - tropics - theory - design
    Mechanized farming in the humid tropics with special reference to soil tillage, workability and timeliness of farm operations : a case study for the Zanderij area of Suriname
    Goense, D. - \ 1987
    Agricultural University. Promotor(en): A. Moens. - S.l. : Goense - 136
    akkerbouw - agrarische bedrijfsvoering - veldgewassen - humide klimaatzones - zaaibedbereiding - suriname - grondbewerking - tropen - arable farming - farm management - field crops - humid zones - seedbed preparation - suriname - tillage - tropics

    The reported investigations concern aspects of mechanized farming for the production of rainfed crops on the loamy soils of the Zanderij formation in Suriname and in particular, the effect of tillage on crop yield and soil properties, workability of field operations and timeliness of field operations. The results were evaluated as to their effect on prospects for mechanized farming in this area.

    The work was carried out within a joint research project of the Agricultural university Wageningen and the University of Suriname.

    The soil in the area of investigation is characterized by a low fertility and high acidity. Natural drainage is good but the water holding capacity is low. The climate in the area is classified as Af according to Köppen, the average rainfall is 2234 mm per year.

    Experiments carried out on the Coebiti experimental farm during a 9 year period, covering 22 cropping cycles, showed that with continued application of conventional tillage consisting of disc ploughing and harrowing, average crop yields were higher than with successive applications of shallow or no tillage. The yield differences varied with crop and conditions, the yield obtained under no tillage was on average about 75 percent of the yield under conventional tillage for maize, sorghum and cowpea. For soya bean this was 85 percent and for groundnuts 90 percent. Shallow tillage like rotavating showed intermediate results. Comparable results were obtained at the Kabo experimental farm covering 4 cropping cycles. Chisel and disc ploughing showed here little difference. With the applied mechanized farming system soil compaction occurs which can be alleviated by soil tillage. The distribution of added fertilizer in the soil reflects the tillage treatments applied. Periodic deep tillage such as ploughing is required to incorporate lime to the appropriate depth to allow deep rooting. From a series of 6 cropping cycles at Coebiti it is concluded that the yield of a no tillage treatment when alternated with conventional tillage can be higher than those obtained under successive application of no tillage. This indicates possibilities for the application of incidental no tillage when workable time for planting is limited. It is concluded that in a mechanized cropping system on these soils, the approach to soil tillage should be flexible. Disc or chisel ploughing, as well as shallow or no tillage can be selected appropriate to crop and prevailing circumstances of field, weather and work progress.

    The limits for workability of disc ploughing and harrowing were determined by measuring the performance of the operations and relating the results to the moisture content of the 0.0-0.20 m soil layer. The maximum soil moisture content for disc ploughing was found to be 13.9 percent wb and for rotary harrowing 13.2 percent wb. It appeared to be too dry for disc ploughing when the moisture content was lower than 10.3 percent wb.

    The measured soil moisture contents and pertaining meteorological data were used in development of a soil moisture model formulated with physical proces descriptions from literature. Expectations of workable time for field operations in so far as limited by rain and soil moisture content were calculated with the model on the basis of a 25 year record of meteorological data at Zanderij station.

    Workability of grain harvesting is governed by the grain moisture status. In field experiments the course of the grain moisture content and attached moisture was determined for maize, groundnut, soya bean, cowpea and sorghum.

    A practical grain moisture model to calculate the grain moisture status in dependence of the weather was formulated and developed with the experimental data and pertaining meteorological data. The hourly course of grain moisture status after maturity was calculated for the 25 year period, allowing calculations of expectations of workable time for harvesting operations with the appropriate limits for grain moisture content.

    The timeliness function for maize planting was calculated with an available model of physical crop production (WOFOST). Available data from maize growing experiments in the area were used for calculating site specific parameters and evaluation of the model. With this model yield expectations were calculated on the basis of the 25 year meteorological record.

    Harvest date experiments were carried out to establish timeliness functions for harvesting of maize, groundnut, soya bean and sorghum. It appeared that crop stand and weather influenced these functions. For maize timelineness costs of up to 100 kg per day were observed under wet conditions in the initial delay period. Under dry conditions timeliness costs were insignificant for the periods considered. For a healthy groundnut crop timeliness costs could be presented by a quadratic function of delay time. Postponement of digging results initially in minor yield reductions per day, the losses per day in the windrow are about four times as high. On a diseased crop losses were much higher. For sorghum observed timeliness costs were between 1.0 and 1.9 percent of initial machine yield per day of postponement of harvesting beyond the date of maturity. The timeliness costs for soya bean harvesting were small in the first two weeks after maturity and increased sharply with further delay.

    The effect of the results of the investigations on the prospects for mechanized farming in the Zanderij area was evaluated with a linear programming model. The evaluation was done for a farm for the cultivation of maize and groundnuts. This farm, equipped with machinery matching a 55 kW tractor, was operated by the farmer on his own except for harvesting operations. Maximization showed that with p-20 values for workable time an area of 35 ha can be cultivated with a cropping index of 1.9. Workable time is limiting farm operations at opportune times and no tillage planting for maize has to be applied for the long rainy season.

    The timeliness costs of harvesting had only small effect on the cropping plan. With p-50 values for workable time a cropping index of 2.5 is obtained in the maximization, in this situation workable time is not limiting farm operations and the option for no tillage planting of maize is not used.

    Workable time is a limiting factor for mechanized farming in the Zanderij area and quantified information is essential for planning. The evaluation provides sufficient indications for strategies to follow to make a mechanized farming system practicable.

    It is concluded that the model type farm is a practicable proposition, provided socio-economic circumstances allow. A high standard of management is required for the proper planning and timing of the field operations.

    Progress and future plans of the project "management of nitrogen in acid low activity clay soils in the humid tropics for food crop production"
    Kang, B.T. ; Kruijs, A. van der; Heide, J. van der - \ 1986
    Haren : IB (Rapport / Instituut voor Bodemvruchtbaarheid 14-86)
    akkerbouw - bacteriën - zware kleigronden - veldgewassen - voedselproductie - humide klimaatzones - uitspoelen - stikstof - stikstofkringloop - stikstofmeststoffen - onderzoek - bodem - bodemvruchtbaarheid - subtropen - tropen - toekomst - arable farming - bacteria - clay soils - field crops - food production - humid zones - leaching - nitrogen - nitrogen cycle - nitrogen fertilizers - research - soil - soil fertility - subtropics - tropics - future
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