Instructie en werkbladen veldpracticum perceelvariatie Bodem
Schans, D.A. van der - \ 2014
Lelystad : PPO AGV (PPO rapporten 634) - 18
onderwijsmaterialen - perceelsvorm (landbouwkundig) - perceelsgrootte (landbouwkundig) - akkergronden - precisielandbouw - bodemvariabiliteit - agrarisch onderwijs - resource materials - field shape - field size - arable soils - precision agriculture - soil variability - agricultural education
Leren waarnemen en weergeven van bodemeigenschappen Bodemvariatie binnen een perceel in kaart brengen Inzicht krijgen in beperkingen/tekortkomingen van de grond voor optimaal gebruik. Opsporen van mogelijkheden om beperkingen van de grond op te heffen.
De onzekere bodemkundige
Knotters, M. - \ 2010
Nederlandse Bodemkundige Vereniging
bodemvariabiliteit - bodemgeschiktheid - soil variability - soil suitability
Onzekerheid heeft zijn oorsprong in gebrek aan kennis. Daarbij komt (bij wetenschappelijk onderzoek) het gebrek aan kennis over variabiliteit. Bij een bodemkundige: een deskundige die te weinig kennis heeft van de variabiliteit van bodemgegevens. Dit essay gaat nader in op dit dilemma van kundigheid en onzekerheid
De akkerbouwer als sensor
Heijting, S. ; Bregt, A.K. ; Bruin, S. de - \ 2010
Agro Informatica 23 (2010)5. - ISSN 0925-4455 - p. 14 - 16.
precisielandbouw - geografische informatiesystemen - bodemvariabiliteit - kennis - agrarische bedrijfsvoering - optimalisatie - precision agriculture - geographical information systems - soil variability - knowledge - farm management - optimization
De ruimtelijke kennis van akkerbouwers over variatie binnen percelen is onderzocht en in kaart gebracht op vier bedrijven in de Hoeksche Waard. Analyse van interviews en bodemmonsters liet zien dat de telers over uitgebreide ruimtelijke kennis van hun percelen beschikken. Grondbewerking, vooral ploegen is een belangrijke bron van informatie over bodemvariatie binnen een perceel. Verschillen in textuur en organisch stofgehalte konden verklaard worden op basis van voormalig landgebruik en ontstaansgeschiedenis van het landschap. Alle telers benutten hun ruimtelijke kennis voor zover technisch en economisch haalbaar. Deze kennis vormt een goed uitgangspunt voor verdere ruimtelijke optimalisatie van de bedrijfsvoering.
"Overslagzand" langs de "Bode" in Bodegraven door een overstroming in de Romeinse tijd; een bodemkundig onderzoek in twee putten langs de Oudbodegraafseweg 24
Mulder, J.R. - \ 2002
Wageningen : Alterra (Alterra-rapport 514) - 28
ouderdom van de bodem - bodemvariabiliteit - zandgronden - geschiedenis - archeologie - overstromingen - nederland - zuid-holland - historische geografie - bodemkunde - Bodegraven - age of soil - soil variability - sandy soils - history - archaeology - floods - netherlands - zuid-holland - historical geography
In opdracht van de Archeologische Werkgemeenschap Nederland (AWN), afdeling Rijnstreek te Leiden is een bodemkundig onderzoek verricht in twee opgravingsputten aan de Oudbodegraafseweg 24 te Bodegraven. Het onderzochte terrein ligt langs de Oude Bodegraaf, een voormalig veenstroompje, achter het terrein waar een Romeins fort heeft gestaan. Aan het begin van de Romeinse tijd bestond de bodem ten zuiden van Bodegraven uit bosveen, het landschap uit elzenbroekbos. Tijdens de Romeinse tijd heeft ten minste één fikse overstroming plaatsgevonden, waarbij over het bosveen een dunne laag overslagzand met schelpresten en aardewerkscherven uit die periode is uitgewaaierd. Gedurende de Vroege Middeleeuwen is hierover een laag beddingklei afgezet. Waarschijnlijk is het veenstroompje de Bode ten tijde van de ontginningen in een stadium van verlanding geweest en hebben de bewoners de bedding weer uitgegraven. In beide opgravingsputten zijn sporen van kleiwinning voor de baksteenindustrie en/of aanleg en onderhoud van kaden en dijken aangetroffen. De kleiputten zijn toegemaakt met amorf broekveen, dat van elders is aangevoerd.
Humusprofielen van het bosreservaat Galgenberg; basisprogramma bosreservaten
Kemmers, R.H. ; Werff, M.M. van der; Waal, R.W. de - \ 2000
Wageningen : Alterra (Alterra-rapport 116) - 33
bossen - natuurreservaten - bodemprofielen - humushorizonten - monitoring - bosgronden - bodemvariabiliteit - ruimtelijke variatie - voedingsstoffen - nederland - utrecht - forests - nature reserves - soil profiles - humus horizons - monitoring - forest soils - soil variability - spatial variation - nutrients - netherlands - utrecht
In bosreservaat Galgenberg (Amerongen) is langs een dwarsdoorsnede in de kernvlakte het humusprofiel beschreven en kwantitatief bemonsterd. Naast gemiddelde waarden en standaardafwijkingen van horizontdikten, nutriëntengehalten, -voorraden en pH werd in het kader van langjarige monitoring ook de ruimtelijke variabiliteit geanalyseerd. De dominante humusvorm is typerend voor wat oudere fasen in de bossuccessie op relatief rijk moedermateriaal. De voorraad koolstof en fosfor in het humusprofiel is groot. De stikstofvoorraad is normaal, terwijl de C-N-verhouding hoog is. Diktes van horizonten en elementvoorraden vertonen een ruimtelijk herhaald patroon van de variantie met een herhalingslengte van 5 tot 20 m.
Humusprofielen in de bosreservaten Hollandse Hout en Houtribbos; basisprogramma bosreservaten
Kemmers, R.H. ; Mekkink, P. ; Waal, R.W. de - \ 2000
Wageningen : Alterra (Alterra-rapport 175) - 23
bossen - natuurreservaten - bodemprofielen - humushorizonten - bosgronden - monitoring - bodemvariabiliteit - ruimtelijke variatie - voedingsstoffen - nederland - flevoland - forests - nature reserves - soil profiles - humus horizons - forest soils - monitoring - soil variability - spatial variation - nutrients - netherlands - flevoland
In de bosreservaten Hollandse Hout en Houtribbos (Flevoland) is in de kernvlakte het humusprofiel beschreven en kwantitatief bemonsterd. In het kader van het basisprogramma bosreservaten werden gemiddelde waarden en standaardafwijkingen van horizontdikten, nutriëntengehalten en -voorraden en pH bepaald. Als dominante humusvorm komt een kalkwormmull voor die typerend is voor kalkrijke leemhoudende gronden. De lage C-N-verhouding wijst op een actief bodemleven en intensieve omzetting van organische stof als gevolg van de gunstige pH-waarden, waardoor slechts weinig koolstof in de Ah-horizonten is geaccumuleerd. Door de accumulatie van organische stof is een beginnende ontkalking aanwezig. In de humusprofielen van de Hollandse Hout is het fosforgehaltesignificant hoger dan in het Houtribbos.
Effectiveness of phosphate rock on ferralsols in Tanzania and the influence of within-field variability
Mowo, J.G. - \ 2000
Agricultural University. Promotor(en): O. Oenema; B.H. Janssen. - S.l. : S.n. - ISBN 9789058082572 - 164
kunstmeststoffen - fosformeststoffen - natuurfosfaat - drievoudig superfosfaat - red soils - ferralsols - mest - peulgewassen - maïs - bodemvariabiliteit - tanzania - fertilizers - phosphorus fertilizers - rock phosphate - triple superphosphate - red soils - ferralsols - manures - legumes - maize - soil variability - tanzania
Crop yields in Tanzania are often limited by P deficiency. Direct application of the locally mined Minjingu phosphate rock (MPR) is considered a possible option in addressing the problem. Being poorly soluble, it is more effective in low pH soils with sizeable P and Ca sinks. In soils rather high in pH, mechanisms are required to promote its dissolution. This research was initiated with the overall objective of increasing our understanding of the multiple interactions affecting the availability of P from MPR in the soil-plant system. This knowledge is required to enable optimal exploitation of the various factors influencing MPR effectiveness for increased crop production. The research program consisted of one laboratory experiment, six greenhouse experiments and four field trials.
The laboratory and greenhouse experiments dealt with single factors influencing the effectiveness of PR under controlled conditions. From the laboratory experiment it was established that the high content of CaCO 3 in Minjingu PR was the major factor that determined the amount of HCl extractable P. However, agronomically it did not differ from Khouribga and Mali PRs, which have relatively lower CaCO 3 content. High application rates lowered the effectiveness of PR pointing to a need to balance application rates with proton supply. In a study relating yield and soil pH, increasing dry-matter yield of maize, cowpea and pigeonpea could not noticeably affect the soil pH mainly due to the pH buffer capacity of the soils. However, when intercropped with maize, cowpea or pigeonpea took up more P from MPR and even improved the uptake of MPR-P by maize. This point to a possible proton induced dissolution of MPR by the legumes. Hence, when intercropping involves legume crops capable of fixing N lower rates of PR can be used which is an attractive option for resource poor farmers. A study on the response of maize, cowpea and pigeonpea to MPR and TSP on soils of low and high pH showed that response to MPR was stronger in the low than in the high pH soil. Both legumes gave a higher DM production with MPR than with TSP on the high pH soil and yields were higher on the high than on the low pH soil. This indicates that the legumes prefer a high soil pH to a low soil pH and are able to make use of MPR at a relatively high pH. The later is possible when the legumes can modify rhizosphere soil conditions with respect to pH.
Maize dry-matter yield response to P on soils with different pH and available P was observed where soil available P was low. There was no yield response to P when P-Bray-I was > 7 mg kg -1 (P-Olsen > 10 mg kg -1 ). Utilization of absorbed P was better from MPR than from TSP in low pH soils indicating a liming effect by the MPR.
Field experiments dealt with multiple factors influencing the effectiveness of PR. The influence of spatial soil variability on the effectiveness of PR and crop performance was studied using the Post-mortem Residual Analysis and Nearest Neighbor Means techniques. These techniques were effective in isolating environmental from treatment effects and they were more useful in the large than in the small trials. A study on the method and rate of P application showed that method of application was more important for MPR in high pH soils and that response to MPR will be obtained at modest rates. The residual effects of TSP and MPR were almost the same. Combined application of MPR and the acidifying fertilizer sulfate of ammonia showed that there is little scope for improving the effectiveness of MPR through the acidifying effect of sulfate of ammonia. Combined application of MPR and TSP gave best results in low pH soils when both of them were applied using the same method. Meanwhile, incubating MPR with farmyard manure could not stimulate MPR dissolution given the high pH of the two materials even after 40 days of incubation (pH (H 2 O) = 8.35). It is concluded that the use of MPR could be extended to less acidic P deficient soils when mechanisms are employed that could stimulate its dissolution. They include use of low amounts of MPR (low input strategy), incorporating legumes in the cropping system and using the same method of application of mixtures of MPR and soluble P fertilizers.
Keywords: Minjingu phosphate rock, triple superphosphate, Rhodic Ferralsols, farmyard-manure, protons, dissolution, legumes, maize, management options, spatial soil variability, Tanzania.
Spatial variability and farmer resource allocation in millet production in Niger
Gandah, M. - \ 1999
Agricultural University. Promotor(en): J. Bouma; J. Brouwer; A. Stein. - S.l. : S.n. - ISBN 9789058080790 - 115
parelgierst - pennisetum glaucum - bodemvariabiliteit - middelentoewijzing - bodembeheer - methodologie - niger - pearl millet - pennisetum glaucum - soil variability - resource allocation - soil management - methodology - niger
The Sahel of West Africa is the agro-ecological zone located between 12 oand 16 oN, with an annual rainfall of between 300 and 1000 mm. Crops are grown in a subsistence type of agriculture during the 75 to 125 days growing period between May and September. Major crops are millet, sorghum, cowpea, and groundnut, sown usually in mixed-cropping. Crop production suffers from frequent droughts and poor soil fertility, which cause low yields and repeated food shortages. Traditional farming, in the western part of Niger, relies on the use of livestock to combat soil nutrient deficiencies, and other risk minimizing strategies, to produce an average 350 kg ha -1year -1of millet grain. This is the context within which this research was conducted in four localities in western Niger in 1995, 1996, and 1997.
The overall aim was to investigate soil and crop variability at various scales and the rightness of traditional land management in millet cropping subject to extremely variable weather conditions. The main objectives were:
Within-field soil and crop variability are discussed in chapters 2 and 3. Grain and straw yields varied considerably within-field at each of the three sites, and also between sites and between years. In 1996, grain yields varied from 8-383 kg ha -1, 2-1343 kg ha -1, and 7-815 kg ha -1at the three sites along a 400 km N-S gradient. The coefficient of variation at the three sites was 61, 55, and 53% respectively. Only 5 to 28% of the yield variability could be explained by soil chemical properties. Other factors such as micro-topography and water redistribution also made yields vary over short distances according to several studies in the region. A millet hill scoring method was tested and refined to obtain yield estimates before crop harvest. Scoring studies have remained at the row or plot level as opposed to the individual hill level. The method was simple and was able to explain up to 67% of the yield variation. Yield variation between years was least at the drier northern site with poorer soil and yields. Variation in yields among years was most closely correlated with soil pH and Al in the northern and central sites, whereas P was the best in explaining grain yield differences in the southern site.
Chapter 4 deals with land management at the individual household level. Soil and crop management were investigated in two fields owned by a Fulani household. Management practices created man-made variability in the fields. Soil nutrient contents were improved in patches through the use of field corralling of livestock and fallow. Quantities of manure applied at specific sites varied from 1500 to 17000 kg ha -1. Corralling increased yields from 500 to 1100 kg ha -1, but amounts of manure applied were too high in some spots and losses were likely to occur through leaching. Nutrients and pH changes in the soil profile were found to change appreciably over time following the application of manure or of fallow. Based on the results obtained, an improvement in the farmer's management can be achieved by spreading manure to an area 3 to 5 times larger than the area actually used.
Chapter 5 focuses on farmers' land management practices according to landscape position. Contrary to common belief, soils on the plateau were richer than soils on other landscape positions, which were cropped continuously and had a sandier texture. Plateaus, however, showed limitations such as low infiltration of rainfall and were located relatively far away from villages. Fields on undulating terraces and valleys had the highest number of different management practices, among which the use of livestock corralling and fallow were the most important.
Chapter 6 considers social aspects of soil management, through the use of ethno-pedology by farmers in ordinary cropping activities. Farmers' knowledge of the land, plants and weather is described as well as the use of this knowledge by farmers in millet production. Simple soil descriptors such as texture, color, surface condition and indicator plants have been used by farmers to evaluate the land. Management practices rely on local knowledge regarding variability in soil fertility and water availability as a guide to implement crop management decisions and to design risk reducing strategies. These compensate in part for the lack of external inputs. The value of ethno-pedology for modern research is that it can serve to better identify farmers' needs and, as a result, improve research quality and the effective communication of results obtained. However, limitations in the use of ethno-pedology exist and they include its inability to quantify factors and the confusion between causes and effects for processes not well understood by farmers.
Spatio-temporal variability of acid sulphate soils in the plain of reeds, Vietnam : impact of soil properties, water management and crop husbandry on the growth and yield of rice in relation to microtopography
Husson, O. - \ 1998
Agricultural University. Promotor(en): L.O. Fresco, co-promotor(en): J. Bouma; E.M.A. Smaling. - S.l. : Husson - ISBN 9789054859253 - 198
rijst - waterbeheer - bodemeigenschappen - bodemvariabiliteit - groei - vietnam - rice - water management - soil properties - soil variability - growth - vietnam
Acid sulphate soils in the Mekong delta cover 1.6 million hectares, of which 400 000 ha are located in the Plain of Reeds. Due to the presence of pyrite that yields acid when oxidised, all acid sulphate soils are (potentially) strongly acidic. Reclamation of the 150 000 ha of severely acid sulphate soils still uncultivated in 1990 became a national priority and now attracts local farmers and migrants. However, these soils present important agronomic problems and farmers urgently need advice to reclaim them. However, the development of recommendations and the cultivation of acid sulphate soils on a large scale are made difficult by their very high variability.
The objectives of this thesis are to:
Spatio-temporal variability in soil and water is very high, at all scales, as explained by the relative soil/water level which influences oxidation, and consequently the soil chemical status in the short term, and soil development in the long term. Soil microtopography is a key factor as slight differences in altitude induce important differences in intensity and length of soil oxidation and mineralisation. This resulted in the differentiation of two very different but closely intertwined soil types, separated by soils with intermediate characteristics. In the study area, located in the central part of the Plain of Reeds, organic Hydraquentic Sulfaquepts occupy locations below 75 cm above mean sea level where soil development is slow because of waterlogged conditions. Upon drainage, these soils are expected to develop into clayey Typic Sulfaquepts with jarosite and goethite mottles as found above 85 cm above mean sea level.
Because of the high sensitivity of plants to soil chemical characteristics, water management which determines redox conditions and Fe and Al concentrations, is a key to the cultivation on acid sulphate soils. Unfortunately, the very high soil permeability makes water control very difficult, especially in the years immediately following reclamation. This makes it difficult to maintain good cropping conditions through irrigation or drainage. Consequently, the time window during which optimal cropping conditions are met is very short. Its starting date and duration are also spatially variable, in relation to microtopography. To extend this time window, farmers in the Plain of Reeds start cultivation as soon as possible, broadcasting pregerminated rice seeds in flood water, before it has completely receded. In these cropping conditions, farmer-managed trials were conducted for four years, after precise site characterisation (using geostatistical methods). Detailed studies of crop phenology and yield led to the development of a semi-quantitative model of rice yield build-up. Yield is mainly determined by panicle density and plant growth, reflected in the weight of one grain.
Within fields, plant, tiller and panicle densities are linearly correlated to microtopography. This has been explained by higher plant mortality and poorer tillering in low positions due to deeper and longer submersion which reduces light intensity, but also to action of sulphate-reducing bacteria in the deeply reduced conditions of the lowest positions. Plant growth can be affected by the deep reduction inducing iron toxicity in the lowest locations. It is, however, mainly limited by aluminium toxicity linked to acidification of the high positions in oxidised conditions at the end of the growing season. This results in plant growth and yield correlated to microtopography in a quadratic trend, with maximum growth at medium topographic level, and with a strong decrease at high topographic levels.
Between fields, similar correlations are observed in the first year after reclamation. With cultivation, improvement of water control results in yield increase every year. This increase is faster on high fields, in which better plant growth can be obtained together with high densities. Thus, after 3 years, average yields of the fields become linearly correlated with the average topographic level, with maximum values at high topographic levels.
Application of this model allows the improvement of water management strategies, based on field characteristics: it determines the proper timing for sowing pregerminated seeds and optimal water management practices, as a function of field topography and age, and flood characteristics.
High fields (higher than 85 cm above mean sea level), and to a certain extend fields at medium topographic level, mainly suffer from acidification at the end of the growth cycle. Water management on these soils should aim at maintaining wet soil to avoid oxidation. In this respect, early sowing, in deep water (30 to 35 cm) is required in the first year after reclamation. Although this leads to lower densities, it is the only way to maintain wet conditions until the end of the cycle and to allow acceptable plant growth. With improvement of water control, sowing can be progressively delayed, until sowing on wet soil becomes possible. In contrast to this situation, low fields (lower than 75 cm above mean sea level) suffer from submersion and deep reduction. Water management should aim at creating a slight oxidation of the top soil as soon as possible. The best practice consists of sowing on wet soil after pumping water out of the field, which is not always possible in the first year after reclamation because of the high permeability.
The model also allows identification of sources of variability in fertiliser experiments conducted on these soils. The advantages of thermophosphate fertiliser over Di-Ammonium phosphate are shown and explained.
Tools and methods to control variability and to use it as information are also presented, such as the use of correlations between microtopography, soil types and natural vegetation for mapping, the proper design and set up of experiments upon precise characterisation of fields and the use of co-variance analysis with microtopography as a covariate.
The results of the study are meaningful to farmers as well as policy makers, and provide a semi-quantitative picture of the dynamics, risks and opportunities for reclamation and agricultural use of acid sulphate soils in the Plain of Reeds and beyond.