<p> SOIL INVESTIGATION – how soil affects plant growth</p><p>Aim: To investigate the structure and properties of different soil types.</p><p>Fill in details of how each factor affects plant growth.</p><p>Soil investigation Impacts on plant growth Soil texture by hand How accurate is this hand test? Is it useful? Could you do your own key?</p><p>The texture triangle: measuring particle size. The texture impacts many other factors such as Texture = the relative proportion of mineral particles of porosity etc..Different soil types have different levels various sizes in soil of productivity – sandy (low), clay (quite low), loam (high) – the surface area (called peds) determines the amount of nutrients/water retained by the soil in solution against gravity. Ph The pH of soil is an important factor in determining which plants will grow because it controls which nutrients are available for the plants to use. Macro nutrients needed for plant growth – NPK – are available in greater amounts around neutral ph 7 and reduce with acidity. Coniferous needles – increase acidity of soils.</p><p>Salinity Soil salinity is a measure of the saltiness of the soil. Many plants have trouble growing in soil that contains too much salt. High soil salinity makes it more difficult for plants to get water from the soil and can interfere with them gaining nutrients. </p><p>Temperature (degrees Celcius) Soil temperature affects climate, plant growth, the timing of budburst or leaf fall, the decomposition rate of organic material, and other biological, chemical, and physical processes that take place in the soil. Cross reference – nutrient cycle model and the size of the soil nutrient store.</p><p>Infiltration test How water flows into and through a soil has great implications for the diversity of plants that can be supported by that soil. Different species of plants will be favoured by a slow versus fast draining soil. Also waterlogging will affect soil growth. Porosity/permeability Pore spaces determine the rate at which water drains through the soil. This affects the amount of water and air available for growth of plants and the nutrient holding capacity of the water. % organic content The amount of humus (plant litter decay) is an important nutrient input into the soil and therefore plant growth. </p><p>% water content Although this is variable depending on climatic conditions it can affect porosity, infiltration. </p><p>SUMMARY</p><p>Primary productivity of soils depends on:</p><p> Mineral content</p><p> Drainage</p><p> Water holding capacity</p><p> Air spaces</p><p> Biota</p><p> Amount of organic matter</p>