Biodiversity: Three replicated trials from Canada, Poland and Spain (including one also controlled, one also randomized and one also controlled and randomized) showed that adding mulch to crops (whether shredded paper, municipal compost or straw) increased soil animal and fungal numbers, diversity and activity. Of these, one trial also showed that mulch improved soil structure and increased soil organic matter.
Nutrient loss:One replicated study from Nigeria found higher nutrient levels in continually cropped soil.
Erosion: Five studies from India, France, Nigeria and the UK (including one controlled, randomized, replicated trial, one randomized, replicated trial, two replicated (one also controlled), and one controlled trial) found that mulches increased soil stability, and reduced soil erosion and runoff. One trial found that some mulches are more effective than others.
Drought:Two replicated trials from India found that adding mulch to crops increased soil moisture.
Yield:Two replicated trials from India found that yields increased when either a live mulch or vegetation barrier combined with mulch was used.
A randomised, replicated, controlled study in Norway found higher survival rates in salmon exposed to infectious pancreatic necrosis if they had undergone aerobic training. Interval training was more effective than continuous training.
Natural enemies on crop trees and vines:Five studies (including one replicated, randomised, controlled test) from Australia, China, Italy and Portugal compared natural and bare ground covers by measuring numbers of natural enemies in fruit tree or vine canopies. Three found effects varied between groups of natural enemies, two found no difference. Two studies from Australia and France compared natural to sown ground cover and found no effect on enemies in crop canopies. Natural enemies on the ground:Five studies (including three replicated, randomised, controlled trials) from Australia, Canada, China, France, and Spain compared natural and bare ground covers by measuring natural enemies on the ground. Two studies found more natural enemies in natural ground cover, but in one the effects were only short-term for most natural enemy groups. Three studies found mixed effects, with higher numbers of some natural enemy groups but not others. Two studies compared natural and sown ground covers, one study found more natural enemies and one found no effect. Pests and crop damage: Four studies (three controlled, one also replicated and randomised) from Italy, Australia and China measured pests and crop damage in regenerated and bare ground covers. Two studies found fewer pests, whilst two studies found effects on pests and crop damage varied for different pest or disease groups. One study found more pests in natural than in sown ground covers.
A replicated, controlled study in Norway reported lower numbers of lice on salmon kept in low intensity artificial light or natural lighting. The more intense the artificial light was, the higher the number of lice found on fish.
Natural enemies: One controlled study from the UK reported more natural enemies when insecticides were sprayed earlier rather than later in the growing season. Pests:Two of four studies from Mozambique, the UK and the USA found fewer pests or less disease damage when insecticides were applied early rather than late. Effects on a disease-carrying pest varied with insecticide type. Two studies (one a randomised, replicated, controlled test) found no effect on pests or pest damage. Yield:Four studies (including one randomised, replicated, controlled test) from Mozambique, the Philippines, the UK and the USA measured yields. Two studies found mixed effects and one study found no effect on yield when insecticides were applied early. One study found higher yields when insecticides were applied at times of suspected crop susceptibility. Profit and costs:One controlled study from the Philippines found higher profits and similar costs when insecticides were only applied at times of suspected crop susceptibility.
Biodiversity: Five controlled trials from China and India (four also randomized and replicated), and one study from Japan found higher microbial biomass and activity in soils with a mix of manure and inorganic fertilizers. Manure alone also increased microbial biomass. One trial found increased microbial diversity.
Erosion: One controlled, replicated trial from India found that mixed amendments were more effective at reducing the size of cracks in dry soil than inorganic fertilizers alone or no fertilizer.
SOC loss: Four controlled, randomized, replicated trials and one controlled trial from China and India found more organic carbon in soils with mixed fertilizers. Manure alone also increased organic carbon. One trial also found more carbon in soil amended with inorganic fertilizers and lime.
SOM loss: Two controlled, randomized, replicated trials from China and India found more nutrients in soils with manure and inorganic fertilizers. One controlled, randomized, replicated trial from China found inconsistent effects of using mixed manure and inorganic fertilizers.
Yield: Two controlled, randomized, replicated trials from China found increased maize Zea mays yield in soils with mixed manure and inorganic fertilizer amendments.