人教版 (2019)选择性必修 第一册Unit 5 Working the Land课文ppt课件

这是一份人教版 (2019)选择性必修 第一册Unit 5 Working the Land课文ppt课件，共9页。PPT课件主要包含了NOW，探究1等内容，欢迎下载使用。
Sustainable Agriculture
9.8 billin by 2050
CHEMICAL VERSUS ORGANIC FARMING
chemical pesticides
artificial fertilisers
in widespread use in farming
Since 1950s
many farmers welcmed
lng-term use harm bth the land and peple's health.
Sme scientists have fund
spraying pesticides n crps
stay in the sil and undergrund water surces fr a lng time
affectsthe crps
the animals and humans
DAMAGETHE LAND
DAMAGEOUR HEALTH
make illcause cancer
Crps grwn with them usually grw t fast t be rich in nutritin. They may lk beautiful n the utside, but inside there is usually mre water than essential minerals, and they ften have less flavur as well.
artificial /man-madefertilisers
Examples (use f pesticides & chemical fertilisers).
withut using any chemicals
keeping their sil rich and free f disease thrugh natural means
Organic farmers als use many ther methds t prduce rich sil. They ften change the kind f crp grwn in each field every year. Fr instance, they may grw crn r wheat in a field ne year, and then
grw beans there the next. Why different crps are grwn is because they put imprtant minerals back int the grund, making it ready again fr the next batch f crps. Organic farmers als plant diverse crps that use different depths f sil t help keep it rich. Fr example, peanuts grw n the grund's surface, but many ther vegetables put dwn deep rts. The gal f using different rganic farming methds is t grw gd fd while aviding damage t the envirnment r t peple's health.