Productivity and farming practices

What the specification says in section 3.4.5: “comparison of natural ecosystems and those based on modern intensive farming in terms of energy input and productivity”

Can you remember the equation for NPP? NPP = GPP – respiratory loss “productivity is affected by farming practices that increase the efficiency of energy conversion” Can you think of any of these practices?

These practices include: The use of natural and artificial fertilisers The use of chemical pesticides, biological agents and integrated systems in controlling pests on agricultural crops Intensive rearing of domestic livestock

Intensive farming is more productive than natural ecosystems because….. It controls the biotic and abiotic conditions to make it more favourable for crops or livestock This means higher productivity and therefore biomass (food!!!)

Independent work Copy the table on p74 A2 book to compare natural and agricultural ecosystems

How do they increase productivity? Reduce energy losses between trophic levels, so increase the efficiency of energy conversion Remove limiting factors for growth so more of the available energy can be used for growth Increase energy input eg more high energy food given to cattle compared to their natural diet

Candidates should be able to: Apply their understanding of biological principles to present scientific arguments that explain how these and other farming practices affect productivity Evaluate economic and environmental issues involved with farming practices that increase productivity Consider ethical issues rising from enhancement of productivity

In groups you will find out about: Natural and artificial fertilisers Pest contol Intensive rearing The cards have questions to be addressed. Each group will produce: a short presentation (5 slides max – can include video) an A4 summary sheet, preferably with bullet points a list of 5 short questions to test recall of the main points Remember to address environmental, economic and ethical issues.

USE: A2 books Revision guides Internet (but don’t get sidetracked!!!!) WORK AS A TEAM!!!!!!

Do the application exercise on p75 “increasing productivity” and check your own answers.