Algeria registers only 0.25 ha of agricultural surface per capita. This indicates very low agricultural capacities. Otherwise agricultural activities are concentrated in a narrow fringe of the Northern part of the cou...Algeria registers only 0.25 ha of agricultural surface per capita. This indicates very low agricultural capacities. Otherwise agricultural activities are concentrated in a narrow fringe of the Northern part of the country where the dominant climate is semi-arid with very irregular rainfalls. A majority of farms produces its main part of income from cereal crops--livestock association system. However, the diversity of the climate and the physical environment, on one hand, and the agricultural policies on the other hand, induce major transformations in this system. Transformations are also the result of a significant demographic growth in rural area. In this context, significant issues appear in term of resource＇s uses and systems＇ sustainability. To shed light in the actual situation, this study, based on a survey of 90 owners, shows that： the intensification can constitute a threat on the pastoral resources; the weakness of the farms encourages the generalization of practices characterised by a weak feed autonomy and a bad management of stock fodders; the animal interspecific integration and partial intensification are positive if they follow models which ensure autonomy, performance and optimal pastoral resource management.展开更多
Organic agricultural systems rely on organic amendments to achieve crop fertility requirements, and weed control must be achieved without synthetic herbicides. Our objective was to determine the crop yield and soil qu...Organic agricultural systems rely on organic amendments to achieve crop fertility requirements, and weed control must be achieved without synthetic herbicides. Our objective was to determine the crop yield and soil quality as affected by a transition from grass to dryland organic agriculture in the Central Great Plains of North America. This study evaluated three beef feedlot compost(BFC)treatments in 2010–2015 following biennial application rates: 0(control), 22.9, and 108.7 t ha^(-1) on two dryland organic cropping systems: a wheat(Triticum aestivum)-fallow(WF) rotation harvested for grain and a triticale(Triticosecale)/pea(Pisum sativum)-fallow(T/P-F) rotation harvested for forage. The triticale + pea biomass responded positively to the 108.7-t ha^(-1) BFC treatment,but not the 22.9-t ha^(-1) BFC treatment. The wheat biomass was not affected by BFC addition, but biomass N content increased.Beef feedlot compost input did not increase wheat grain yields, but had a positive effect on wheat grain Zn content. Soil total C and N contents increased with the rate of 108.7 t ha^(-1) BFC after three applications, but not with 22.9 t ha^(-1) BFC. Soil enzyme activities associated with N and C cycling responded positively to the 108.7-t ha^(-1) BFC treatment. Saturated salts were high in the soil receiving 108.7 t ha^(-1) of BFC, but did not affect crop yields. These results showed that BFC was effective in enhancing forage yields, wheat grain quality, and soil C and N, as well as specific microbial enzymes important for nutrient cycling. However, the large rates of BFC necessary to elicit these positive responses did not increase grain yields, and resulted in an excessive buildup of soil P.展开更多
文摘Algeria registers only 0.25 ha of agricultural surface per capita. This indicates very low agricultural capacities. Otherwise agricultural activities are concentrated in a narrow fringe of the Northern part of the country where the dominant climate is semi-arid with very irregular rainfalls. A majority of farms produces its main part of income from cereal crops--livestock association system. However, the diversity of the climate and the physical environment, on one hand, and the agricultural policies on the other hand, induce major transformations in this system. Transformations are also the result of a significant demographic growth in rural area. In this context, significant issues appear in term of resource＇s uses and systems＇ sustainability. To shed light in the actual situation, this study, based on a survey of 90 owners, shows that： the intensification can constitute a threat on the pastoral resources; the weakness of the farms encourages the generalization of practices characterised by a weak feed autonomy and a bad management of stock fodders; the animal interspecific integration and partial intensification are positive if they follow models which ensure autonomy, performance and optimal pastoral resource management.
文摘Organic agricultural systems rely on organic amendments to achieve crop fertility requirements, and weed control must be achieved without synthetic herbicides. Our objective was to determine the crop yield and soil quality as affected by a transition from grass to dryland organic agriculture in the Central Great Plains of North America. This study evaluated three beef feedlot compost(BFC)treatments in 2010–2015 following biennial application rates: 0(control), 22.9, and 108.7 t ha^(-1) on two dryland organic cropping systems: a wheat(Triticum aestivum)-fallow(WF) rotation harvested for grain and a triticale(Triticosecale)/pea(Pisum sativum)-fallow(T/P-F) rotation harvested for forage. The triticale + pea biomass responded positively to the 108.7-t ha^(-1) BFC treatment,but not the 22.9-t ha^(-1) BFC treatment. The wheat biomass was not affected by BFC addition, but biomass N content increased.Beef feedlot compost input did not increase wheat grain yields, but had a positive effect on wheat grain Zn content. Soil total C and N contents increased with the rate of 108.7 t ha^(-1) BFC after three applications, but not with 22.9 t ha^(-1) BFC. Soil enzyme activities associated with N and C cycling responded positively to the 108.7-t ha^(-1) BFC treatment. Saturated salts were high in the soil receiving 108.7 t ha^(-1) of BFC, but did not affect crop yields. These results showed that BFC was effective in enhancing forage yields, wheat grain quality, and soil C and N, as well as specific microbial enzymes important for nutrient cycling. However, the large rates of BFC necessary to elicit these positive responses did not increase grain yields, and resulted in an excessive buildup of soil P.
