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what are zonal soils dictated by

climate and vegetation


semi arid brown and pallic are all zonal soils list them from low to highest rainfall

semi arid


pallic soils

- Winter – wet due to being imperfectly drained
- Summer – bake hard and dry and pasture browns off readily
- Climate : subhumid (500- 1100mm) in areas with summer soil moisture deficit and winter moisture excess
- Vegetation: formed under swampy podocarp-broadleaf forest
- Relief: dominantly flat to gently rolling river and marine terraces
- Parent materials: normal silicious parent material mineral rich in quartz formed in last 15,000 – 30,000 years due to landscapes being constructed/ eroded during the last glaciation
- Distribution: HB, Manawatu, Malbourgh, canterbury
- Often requires man made drainage

- Physical properties = high dry bulk density horizons and low permeability in the Bg horizon which results in a perched water table prone to pugging in winter and in the summer due to the climate and it being a soil prone to compaction leading to very few macropores means water stress is common for plants in the summer.

- Chemical properties = weak weathering, low om due to it being oxidized easily in these climate conditions

- Uses ; gently rolling land and rainfall above 900mm pallic soils are used for dairying in the north island if below this normally struggle in summer and require lots of feed supplementation and irrigation they often require mole and pipe drainage as the major limitation to this soils is its poor drainage


brown soils

- Occur in humid areas with rainfall greater than 1000mm
- Soil profiles remain moist throughout the year (moisture deficit in summer not pronounced = summer safe)
- Most extensive soil order in new Zealand
- parent material: normal silicious parent material mineral rich in quartz formed in last 15,000 – 30,000 years due to landscapes being constructed/ eroded during the last glaciation
- well drained
- has the capacity to produce fe and al oxyhydroxides due to the insitu weathering which offers greater to protection to OM
- granular structure soils levin brown soils famous for growing veges due to properties such as moderate macroporsity high level of readily available water especially in the stop soils
- no dense fragipans or iron pans
- good soils for a range of different uses grazing , recreation, forestry
- High production achieved by maintain ph


ultic soils

- Found in deeply weathered fine textured sliica rich sedimentary rocks
- Cimate = warm climate rainfall > than 1200mm which explains why they are deeply weathered
- Biological activity determined by acidity of the soil and podalization due to being more weathered activity is lower than other soiks
- Found on a variety of reliefs but not normally where erosion is common
- Parent material = clay rich and tend to form podzols
- Occur on older landscapes
- Found up in northland and western waikato
- Due to weathering both farming an forestry require careful monitoring of macro and micro elements


podzol soils

- Rain fall is greater than evapotranspiration
- Form under the mor vegetation, litter accumulates on the soil surface
- Quite acidic soils so very little earthworms or microbes to mix soil
- Organic complexes move down profile due to high rainfall producing an E horizon as the fe and al oxides are stripped leaving behind quartz gives that pale whit colour
- Om and fe/ al then gather under the e horizon
- Need stable landscapes and long time to develop
- Often poorly drained due dense b horizon
- Would have been better if they were left in natural vegetatation due to huge fertilizer requirements and drainage issues


recent soils

- Form on alluvium the type is based on where the river is located in the country
- Found on floodplains, low terraces where there is periodic distribution of alluvium
- Due to this chemical physical and biological properties differ widely
- They are unified by being young and less affected by the climatic regieme than older soils
- Occupy moderately to well drained positions in the landscape
- One of most valuable soil resources in the country – wide variety of crops grown suited to the local climate it is in


organic soils

- More than 25% OM in top soil
- Occur in a range of climates
- -intrazonal soils
- Poor drainage and aeration
- Main use dairy farming


pumice soils

- Formed from volcanic rocks
- Weakly weathered thin a horizons
- Low bulk density – pumice floats – leads to erosion problems
- Very porous which mean RAWC is theroectically high but in practice is drought prone
- Pine trees succeful on pumice soils
- Deficient in CO = bush sickness
- Being converted back to dairying


allophanic soils

- Formed on volcanic rocks
- Loamy textures
- Well drained
- Top soils dark with high om due to allophane stabilizing it and protecting it
- Many macropores
- High variable charge
- Jigh p retention
- Good physical properties for plant growth
- Wide range of uses best dairying soils and kiwifruit in bop


granualar soils

- Older and more weathered than allophanic sois so are dominated by halloysite
- Significant clay presence dictates this soils behaviour physically and chemically
- Often stick when wet
- Found in humid areas of NI
- Mainly veatables produced on it