لمعلومات أكثر عن مقاومة الأعشاب الضارة والأمراض بفضل السماد الأخضر:
http://www.cogs.asn.au/wp-content/up...eenmanures.pdf
Weed control: Green manures tend to outcompete
weeds for water, light and nutrients. As they grow,
manure crops prevent weeds from colonising bare
ground left after the preceding crop has been removed.
Soil stability: Growing a green manure crop protects
the soil surface from wind and water erosion and
prevents leaching of nutrients.
Pest and disease management: Using green manures
in a crop rotation system can help disrupt pest and
disease cycles. Some manures release natural
chemicals into the soil, some act against soil-borne
diseases and nematodes and some attract
beneficial parasitic insects to the garden.
Green Manures for Vegetable Cropping - Department of Primary Industries
Weed control:
Weeds are suppressed by the competition that dense, green manure crops exert for water, light and nutrients. Short-term green manures therefore provide organic growers with a productive, chemical-free and reduced-cultivation option for weed management during non-crop phases of their vegetable crop rotation.
Pest and disease management:
Pest and disease cycles can be disrupted by the use of non-vegetable green manure crops in the crop rotation program. Some green manure plants, including cowpea, have extra-floral nectaries that attract beneficial insects like parasitic wasps to the cropping area. Others, like mustards, release natural chemicals into the soil and provide some bio-fumigant action against soil-borne diseases and nematodes. Thoughtful use of such green manures can benefit the overall cropping system whilst contributing to soil improvement.
Which Green Manure Should I Grow? - Department of Primary Industries
Weeds, pests and diseases suppressed (incl. allelopathy)In this column, data is given on the effects of green manure/cover crops on weeds, vegetable pests and diseases. Weeds, pests or pathogens may be suppressed through an allelopathic affect. Allelopathy refers to the effect that plants or micro-organisms have in stimulating or inhibiting the growth of neighbouring plants or micro-organisms through the production of organic compounds.
Allelopathy is an important attribute for pest and disease control. For example, biofumigation by plants from the brassica family is grounded on allelopathy. Brassicas contain chemicals, called glucosinolates, which are basic substances for the formation of the chemicals isothiocyanates that suppress soil pathogens. Weeds may also be suppressed by strong competition, mainly for light, but also water, from the green manure/cover crop. Pests and pathogens may be reduced, when the green manure crop acts as a ‘break crop’, i.e. it is not a host to the pest or disease and thus breaks its lifecycle.
Host of these vegetable diseases and Host of these vegetable pestsMost green manure/cover crops are susceptible to, or hosts of, pests and diseases that are crop specific and do not affect vegetables. Those pests and diseases are not listed. For example, the cereal root disease ‘Take-all’ (Gaeumannomyces graminis) may affect a barley green manure crop but will not affect the next vegetable crop.
Some pests and diseases, however, may attack a green manure/cover crop as well as a vegetable crop. In this case, it is important to weigh up the potential risks of these pest and disease effects against the benefits, when choosing crops. Pests and diseases might proliferate in the green manure/cover crop and attack the following vegetable crop. On the other hand, a low level incidence of pests in the green manure crop may not excessively diminish the green manure’s growth and can have the benefit of being a food source to attract and allow the survival of beneficial insects that will then protect the cash crop.
كما أن السماد الأخضر يساعد على وجود وتوفير الغذاء اللازم للعشبيات النافعة والحشرات المفيدة للنبات
Host/habitat for these beneficial insectsAn important function of green manure/cover crops is to provide food and shelter for beneficial insects. Most crops do this to some degree. Prolific bloomers especially, are a source of nectar and pollen, important food sources for insects. Some crops are well known for supporting beneficial insects particularly well and they have been listed.