SOIL HEALTH

What is soil?

is not dirt, is a living organism and contains mineral, organic matter, air and water, relies on microbes to make nutrients accessible to plants and earthworms to bring nutrients down to microbes

What is nitrogen used for in agriculture ?

is applied to the land, need microbes to convert organic nitrogen from plant matter, dead animals and urea, to NH4+ that plants can use, nitrogen is the rate limiting step of plant growth as requires specialised bacteria to take it out of the atmosphere

Why may applying excess nitrogen not help plant growth?

if more nitrogen is present than plants can use, it will leech

What is the change phosphorus utilisation?

NZ soil concentrations are low typically due to crop production or high due to heavy fertiliser use, phosphorus is a non-renewable energy source which when lost from the land goes down the drain to the oceans which is much faster than natural processing

What is the relationship between plants and microbes?

beneficial relationship because plant puts out sugar for microbes to use and plants can access nutrients because of microbes

What are some damaging soil practices?

plowing, soil loss, soil compaction

Why is plowing detrimental to soil health?

disrupts the soil biological structure

What is soil loss?

when soil is removed from where it was formed usually by erosion or poor land management, this isn’t good as it takes away organic matter and nitrogen but it is difficult to not expose soil in cropping systems

What is soil compaction?

soil is compressed by livestock or heavy machinery etc, plant roots may struggle to get past a certain layer of soil, channels are lost and water may pool here

What are some innovations to regenerate soil and improve soil health?

no tilling, cover cropping, composting and crop rotation

What is no till?

replacement for plowing, is a disc which open the earth, drops the seed inside and drops the earth back, less erosion, compaction, time and fuel but equipment is costly and may require more agrichemicals to kill existing plant material so that seed can embed in soil

What is cover cropping?

planting a crop that is for protection of soil and not for harvest, can either leave to grow or to die because would put C + N back into the soil

How does composting work?

could replace chemical fertilisers on farms, microbes require a balance of C + N to break down organic matter, if N is low - C won’t be broken down as microbes need N for food, if low C:N ratio faster decay of soil organic matter

What is crop rotation?

different crops do different things for the soil e.g legumes put C + N into soil, so rotating where they are planted can be advantageous

What is the ideal pH for crops and the natural pH of NZ soils?

between 5-7 is typically optimal and NZ soils typically between 4-5

What can be applied to the soil if it is too acidic?

lime

What can be applied to the soil if its too alkaline?

sulphur containing fertiliser

What does aluminium do to plants?

if pH is low, aluminium in soil will attack plant roots but if pH>5 aluminium in soil will not affect roots

What does copper do to plants and how to resolve the issue?

stunts their growth but with lime added, this raises soil pH making copper unavailable to plants

What does farmer from Gimmerburn NZ do?

regenerated soil health by killing old plant material and applying lime to bring up soil pH, grows mixed pasture for different crops and maintains soil moisture which extends grass growing season allowing his livestock to stay on pasture for longer, stay at the farm for longer because grows enough feed for them, more likely to reach a higher weight before going to the works