An organic vegetable crop rotation aimed at self-sufficiency in nitrogen

The paper describes the organic vegetable crop rotation. The ideas behind the design of the crop rotation, the use of green manures and catch crops, and how information on crop root growth has been used to try to design a crop rotation with a high NUE and minimal N leaching losses. The results from the first years of the rotation, in terms of yield and N uptake of the crops and of the content of inorganic N in the soil are presented

Brassicas in sustainable production and organic farming

Brassica plant species show some characteristics in their use of plant nutrients which make them different from most other crops. These characteristics often make brassicas difficult to grow in low-input systems with limited nutrient availability, but at the same time they also make some brassica species valuable tools for reducing nitrate leaching losses and improving N management in farming systems. The paper presents experimental results on brassica crops as main crops and cover crops

Combining agronomic and breeding approaches for improved nutrient use efficiency

There is a strong need to improve agricultural nutrient use efficiency (NUE), but NUE is complex, and not even well defined. The abstract and presentation deal with how NUE is determined by the combination of Genetic, Environmental and Management factors (GxExM), and how genetics as well as crop management must be combined in order to achieve improved overall NUE

Comparing conventional and improved organic vegetable rotations, yields and nitrogen husbandry

During 2005 to 2009 three approaches to organic vegetable rotations were compared to a conventional rotation in an interdisciplinary project. The organic rotations differed in their reliance on animal manure vs. cover crops and intercrops, but the rotation of main vegetable and cereal crops were identical in the four rotations. One organic rotation (O1) relied on import of manure for supply of nutrients, in another (O2) cover crops were used to replace most of the manure import, and in (O3) also intercrops were grown to improve natural pest regulation. The yearly import of nitrogen were on average 149, 94, 28, and 28 kg N.ha-1 in C, O1, O2, and O3 respectively. On average the yield in the O1 system was 83% of the yield in the conventional system. In the O2 rotation the yield was the same, though the nutrient import was much lower, whereas the intercrops in O3 reduced the yield to 70% of the conventional fotation. The effect on single crops varied with organic yields ranging from 60% (onion) to almost 100% (carrots, oats) of conventional yields. Crop root growth varied strongly among crops with rooting depths of less than 0.4 m (onions) to more than 2 m (cabbage, rye, fodder radish catch crop). Root growth was unaffected by cropping system, but the inclusion of deep rooted catch crops and green manures in O2 and O3 increased the total root exploitation of the soil strongly. Thus, while the O1 and O2 systems had almost identical yields and N uptake there were large differences in their effects on soil N; e.g. the subsoil (1-2.5 m) N content was on average 18 kg N.ha-1 in the O2 compared 61 and 53 kg N.ha-1 in the C and O1 respectively, indicating strongly reduced N leaching losses in O2

Relation between growth characteristics and yield of barley in different environments

The increasing interest in organic farming has increased the interest in examining the importance of the different growing characteristics, such as attack of diseases, grain weight, lodging and heading date. One of the important questions raised was whether the relationship between the growing characteristics and yield would be the same for conventionally and organically grown crop or would some growing characteristics be more important for organically than for conventionally grown crops. This work will focus on that question. The analyses are performed using two datasets with comparable trials in both conventional and organic grown systems for barley (Hordeum vulgare). The two datasets were from Sweden and Denmark. From Sweden 22 conventional and 22 organic grown trials were available. The trials were laid out at 4 locations in Northern Sweden during the years from 1994-2003. The number of varieties per trial varied between 7 and 15 and 50 varieties were represented. Most of the trials were laid out as split-plot designs with 2 nitrogen levels in the conventional grown trial and 2 seed rates in the organic grown trials. From Denmark 4 conventional and 4 organic grown trials were available. The trials were laid out as a-designs at 2 locations in 2 years (2003 and 2004). The number of varieties per trial varied between 108 and 113 and 146 varieties were represented. The data from each country were analysed in a linear mixed model. The effects of location, year, variety, their interaction and interaction with system were included as random effect. The effect of growing system and growing characteristics were included as fixed effects to see how much of the variation caused by varieties and interaction with varieties that could be explained by the growing characteristic and to se if the effect of the growing characteristics depended on the growing system. The analyses showed that the growing characteristics could explain a considerable part of the variance components for variety or interaction with variety. The effect of some growing characteristics depended significantly on the growing system, but the results varied to some extent between the two countries. In Sweden the effect of volume weight were more important in the conventional grown trials than in the organic grown trials whereas in Denmark grain weight was more important in the organic grown trials than in the conventional grown trials. In Denmark powdery mildew decreased the yield significantly more in conventional grown trials than in organic grown trials. In most cases the other diseases decreased the yield more in the organic grown trials than in the conventional grown trials. In some models the yield in organic grown trials increased as the level of scald attach increased. The results indicated that the effect of a given disease level decreased the yield more in the conventional grown trials than in the organic grown trials – or in some cases increased the yield in the organic grown trial while the yield in conventionally grown trials were increased less or decreased

Effects of catch crops on the content of sulfur (S) and selenium (Se) in vegetables

Selenium is an essential nutrient for animals, humans and microorganisms. Se deficiency in humans has been linked to a plethora of physiological disorders. Increasing evidences point to an anticarcinogenic potential of Se-compounds. To address Se deficiency in the human diet, agronomists and plant breeders are pursuing complementary strategies to produce crops with greater Se concentrations. Catch crops have been used successfully in agriculture, increasing nitrogen and sulfur content in the soil and avoiding nutrient leaching. In this experiment we study whether catch crops can have similar beneficial effects regarding Se

Modelling root distribution and nitrogen uptake

Plant soil and atmosphere models are commonly used to predict crop yield and environmental consequence. Such models often include complex modelling modules for water movement, soil organic matter turnover and, above ground plant growth. However, the root modelling in these models are often very simple, partly due to a limited access to experimental data. We present a two-dimensional model for root growth and proliferation. The model focuses on annual crops, and attempt to model root growth of the crops and its significance for N uptake from different parts of the soil volume

Intra-Row Weed Control by use of Band Steaming

Disinfection of the soil by means of steaming has been a common method for eliminating weeds and fungal diseases. However, surface steaming of soil is a very energy-intensive process, and consequently, efforts have been made to develop a machine for narrow-band steaming of the soil under and around rows of cultivated plants prior to seeding. The use of this machine may achieve up to 90% energy savings, and will also reduce the amount of damage to the flora and fauna. Tests have shown that soil temperatures exceeding 70C will be needed to protect against germination of weed seeds. For band heating such a treatment in 50 cm rows requires about 5.8 GJ/ha

Optimizing a green manure-based row cropping system for organic cereal production

A row cropping system with an increase of row distance to 24 cm increased the growth of undersown cover crops and allowed 1-2 passes of interow hoeing for weed control before sowing cover crops. The three-week delay sowing time was suitable for the growth of legume species. The new system significantly improved both grain yield and grain N content of the succeeding crop compared to the traditional cropping system

GROWING MEDIA FOR ORGANIC TOMATO PLANTLET PRODUCTION

The choice of growing media and the strategy of application of organic fertilizers is considered one of the largest challenges for production of organic tomato plantlets for transplanting. We have measured the growth and the ability of young tomato plantlets to extract plant nutrients from an organic growing media. Plants were grown in 0.45L pots. Plant nutrition were either entirely based on the mineral nutrients, available from the organic growing media or based on a combination of nutrients from the organic growing media and fertigation with water-soluble organic fertilizers during plantlet production. The first results shows that plant dry weigth and uptake of nitrogen, phosphorus and potassium was reduced in the organic growing media compared to the control, peat based growing media, but the results also indicate a possibility for optimizing the suggested organic growing media in order to increase the nutrient acquisition and utilization efficiency of the plants. Improved organic growing media can supply most of the necessary plant nutrients needed for the plant, limit the need for supplementary fertilisation, and be an alternative to conventional production with inorganic fertilizers