soil biodiversity

Question 1

what are the 2 types of primary consumers

Answer 1

comsumers of primary producers eg herbivores and detritivors (eating dead tissue) main decomposers

Question 2

what are primary producers

Answer 2

producing organic substances from inorganic eg plants and algae

Question 3

what are secondary consumers and what are their benefits

Answer 3

predators and microbial feeders (these may enhance OM decomposition through reducing competition and through biotubation

Question 4

what are the 3 types of earthworms

Answer 4

1. epigeic (live in litter and ehnace decompostion but do not bioturbate)
2. endogeic (living in top soil take litter into top soil)
3. anecic (make vertile permanment burrows m deep.

Question 5

positive effects of earthworms (4)

Answer 5

1. improve root penetration
2. bioturbation
3. make casts which increase soil structure
4. decomposition and mineralisation enhanced

Question 6

negative effects of earthworms (2)

Answer 6

1. can remove litter which exposes soil forming crusts and risk of erosion
2. channels may help nutrient leeching

Question 7

how does soil moisture affect nematodes and protozoa

Answer 7

they need moisture to be active however dry soils do not kill them they maintain in resting state (coils and cysts)

Question 8

how are nematodes a risk to crops

Answer 8

they can be plant parasites and cause infection by secondary pathogens.

Question 9

how can the nematode risk be managed

Answer 9

nonhost crop rotations, genetically resistance crops, rotation with crops that produce nematicide properties eg mustards and radish

Question 10

what is the largest organism group by weight in the soil

Answer 10

fungi

Question 11

what are the 2 types of fungi

Answer 11

1. yeats need water and oxygen

2. molds and mushrooms

Question 12

examples of fungi that decompose simple sugars one that decompose complex lignin

Answer 12

1. sapropphytic fungi (easy)

2. white rot fungi (complex)

Question 13

what are mycorrhizal plants

Answer 13

most plants are mycorrhizal. it is the symbiosis with mycorrhizas fungi that lives on the root, they prodice nutrients and water in return for carbon

Question 14

what are the two types of mycorrhiza ?

Answer 14

1. ecto
   they penerate the root and develop around the free space of the cells
2. endo (arbuscular AM)
   penetrate root cell walls and form structures called arbuscular. these obtain P, transfer nutrients, good for crops

Question 15

managing mycorrhizas

Answer 15

good for crops, reduce tillage as that destroys hyphal networks
prefers low nutrient levels therefore do not add fertilisers

Question 16

soil conditions affecting growth of microbes (5)

Answer 16

1. OM
2. oxygen
3. moisture
   .4. temperature (greatest between 20-40 deg)
4. pH, bacteria balacned soils, fungi acidic soils

Question 17

overall benefits of organisms (5)

Answer 17

1. breakdown SOM, nurtient cycling, structure
2. breakdown toxic compounds
3. nitorgen fixation
4. rhizobateria promote plant growth
5. plant protection by parasites and pathogens

Question 18

overall negative effects of organisms (2)

Answer 18

1. pests and parasites ie larvae

2. plant disease, fungi wilts, rots etc bacteria stunting nurtient deficentcy