Excessive use of agrochemicals in conventional crop management has caused serious environmental and health problems including loss of biodiversity and human disorders.

-Dynamics of weed populations in arable fields are influenced by environmental and soil characteristics and also by cropping system and management practices. Manipulation of cropping systems to improve weed management requires a better understanding of the spatial and temporal dynamics of weeds, seed losses and seed production. To assess the effect of different cropping systems and various crop rotations on the weed population and seed bank, we conducted a field study at the experimental farm in Khorasan Agricultural Research Center, Mashhad, Iran. The experimental design was a split plot with 3 crop rotations as the main plots, and five cropping systems consisting of high-input, medium-input, low-input, organic and integrated systems applied to the sub-plots. Our results show that weed seed densities in organic and integrated cropping systems, of about 5000-6000 seeds/m 2 were higher than conventional and high-input cropping systems showing about 2000 seeds/m 2 . Weed seed density in continuous winter wheat of approximately 6300 seeds/m 2 was higher than other rotations with about 5000 seeds/m 2 . Weed composition in the high-input system was 11 species with 66 plants/m 2 . Whereas in the low-input and organic systems, the weed populations were 15 and 13 species with 145 and 220 plants/m 2 , respectively. Changes in weed seed bank density and species composition often occur when crop management practices and crop rotations are altered. For example, continuous winter wheat fields showed more annual grass weeds, but broadleaf weeds were more abundant in sugar beet-winter wheat rotation. The weed population in continuous winter wheat plots comprised 90% grass and sedge weeds, while in sugar beet-wheat rotation, it was only 43% of total weed density. Broadleaf weeds were 55.2% in sugar beet-winter wheat but 9.4% of total weed density in continuous winter wheat. Different rotations that include crops with different life cycles such as winter wheat-maize and winter wheat-sugar beet could lead to additional benefits of reducing the weed seed bank.conventional agriculture / ecological farming / integrated crop management / low-input crop production / organic farming

No abstract

The sustainability of a farm system greatly relies on fertilizers and other inputs. Soil factors such as texture and local rainfall, along with management-related factors such as soil organic matter, aggregate stability and agronomic practices, have much greater influence on the sustainability of any given farm than do the type or amount of soil amendments. Growers use a wide variety of practices to maintain or improve soil health in organic vegetable production systems. These practices generally are part of long-term, site-specific management programs that aim at developing fertile and biologically active soils that readily capture and store water and nutrients, have good tilth, and suppress plant diseases. Field experiments were conducted in 2005 and 2006 in Mashhad, Iran, to study the effects of organic amendments, synthetic fertilizers and compost extracts on crop health, productivity and storability of tomato (Lycopersicon esculentum Mill.). Treatments included different fertilizers of cattle, sheep and poultry manures, green-waste and household composts and chemical fertilizers of urea and superphosphate; and five aqueous extracts from cattle manure, poultry manures, green-waste, and household composts plus water as control. Our results show that application of poultry manure showed lower disease incidence, as shown by 80% healthy tomato, compared with the other fertilizers. However, the organic fertilizers used did not give higher yields compared with chemical fertilizers. Sheep manure and chemical fertilizers led to the highest total tomato yield. Marketable yield was highest in poultry manures, of 16 t/ha, and lowest in chemical fertilizer, of 7 t/ha, 6 weeks after storage. The effect of aqueous extracts was not significant on either crop health or tomato yield and the results were inconsistent. The compost made of poultry manure therefore appears to be a promising ecological alternative to classical fertilizers. compost / crop health / lycopersicum esculentum / manure / marketable yield

Optimisation of water and nitrogen use is an effective management tool to conserve resources and reduce environmental pollutions. Response surface methodology (RSM) is defined as a collection of mathematical and statistical methods that are used to develop, to improve or to optimize a product or process. In order to determine optimum levels of water, nitrogen and planting density of canola (Brassica napus L.), a 2-year experiment (2010-2011) was carried out by central composite design as RSM at the research station of Ferdowsi University of Mashhad. The treatments were designed based on low and high levels of irrigation (1500 and 4000 m 3 ha −1 ), nitrogen (0 and 400 kg N ha −1 ) and density (50 and 150 plant m −2 ) as independent variables. Furthermore, seed yield, nitrogen losses, nitrogen use efficiency (NUE) and water use efficiency (WUE) were measured as response variables in a full quadratic polynomial model. Optimum levels of irrigation, nitrogen and planting density were suggested to achieve the target range of dependent variables based on three scenarios: economic, environmental and eco-environmental. The results showed that increasing irrigation and fertilizer led to an increase in seed yield and nitrogen losses, whereas increasing canola density resulted in an increase in seed yield but a decrease in nitrogen losses. The optimum levels of water, fertilizer and density based on environmental scenario were 1802 m 3 ha −1 , 11 kg N ha −1 and 122 plant m −2 , respectively. To achieve optimum conditions under the economic scenario, it is necessary to use 3411 m 3 water ha −1 , 178 kg N ha −1 and 119 plant m −2 . Amounts of 2347 m 3 water ha −1 , 92 kg N ha −1 and 114 plant m −2 were found to be the optimum conditions for the eco-environmental scenario. In general, it seems that resource use based on the eco-environmental scenario may be the most favorable cropping strategy for canola production.

The effect of six intervals between harvests and three levels of N application on the proportion and yield of green leaf, dead leaf, 'stem' and inflorescence was studied in four ryegrass (Lolium) varieties during a 30-week period in the first harvest year in a field experiment. In one variety, S.23, the 'stem' was divided into true stem, leaf sheath, unemerged leaf and unemerged inflorescence.

No abstract

No abstract