The aim of phasing out the use of conventional manure makes it more difficult to secure sufficient nutrients in organic crops. This project seeks to solve this challenge i.e. by studying whether genotypes with superior root traits are better at using nutrients from the composts, and whether some wheat genotypes vary in their ability to utilize compost to achieve god baking quality.

We will develop and test improved compost products, and develop bread baking including the use of natural additives to enhance backing quality.

Demonstration activities will be related to all parts of the project. Composts will be tested for different wheat types at organic farms and differences in root traits or baking quality will be demonstrated at open field days.

2013: Progress and activities:

A core activity is to study cultivar variation in root growth. Good root growth is important when plants need to cope with limited nutrient availability, but the cultivars we grow have been breed under conventional farming conditions and have not been selected for characteristics related to good performance at low nutrient availability. We focus on differences in early root growth and architecture, as at this early stage, the root system is still small and only in contact with a small fraction of the soil and its nutrients. At the same time nutrient availability is often low at the time when crops are established in the spring, the soil is still cold and nutrient mineralization therefore limited. 

We have developed a rhizotron system which has allowed us to show differences among genotypes in vertical as well as horizontal root growth. We have selected cultivars of spring wheat, current as well as older, and cultivars of spelt and emmer wheat, to make sure the studies included a broad genetic variation. We have found significant differences in early root growth, initiation of root branching, distribution of the roots within the soil volume and in the formation of root hairs. 

Evaluation of results from hydroponic studies and rhizotrons has shown that there is a correlation of early root growth vigour under low P conditions, whereas nutrient uptake did not correlate well between soil and hydroponic systems. This in turn indicates that hydroponic studies may assist the screening genotypes of spring wheat for early root growth vigour, but cannot stand alone and must be combined with soil based testing. These studies have been written up, and uploaded to Organic eprints (Wang et al. submitted; and Wang et al. in preparation).

During 2013, we have made field studies investigating how these differences in root traits affect the establishment, development of tillers and leaf area of these genotypes when sown on a soil with low nutrient content. The results of these trials have not been finalized at this writing, but indicate clear differences in the genotypes ability to grow at different fertility levels, in line with the differences observed in the rhizotron studies. 

The results on cultivar differences in root growth have also been used to select cultivars for larger field studies at two organic farms in 2012 and again in 2013, where interaction between cultivar and nutrient use from different compost types was investigated. 

Within the project we study use of plant nutrients from various kinds of urban waste as nutrient sources for organic farming. We have produced composts based on different nutrient rich sources such as fruit and vegetable residues and sewage sludge. They have been composted with other materials mainly contributing structure and organic matter, such as green garden waste. The choice of urban wastes includes relatively unproblematic sources, as well as types such as sewage sludge which are more problematic and not presently al-lowed as fertilizers in organic farming. In 2014 we will make studies of the use of more nutrient rich compost as “placed fertilizer” in an attempt to increase the nutrient use from the compost.

Through an analysis of potentially available sources of nutrients from urban waste we have found that they are presently high compared to the need for nutrient import for organic farming in Denmark. However, this is based on the current situation where only 7% of the Danish farm land is grown organically. As much as 50% of the total N and 80% of total P from urban sources are found in sewage sludge, and only ca. 30% of N and 8% of P are found in urban sources (garden/park waste and household waste sorted at the source) which can be less problematic to use in organic farming.

The conclusion is also based on the use of all available nutrient sources, including the more controversial ones. If only the less problematic types of urban waste are considered the contribution will be small.  This has been elucidated in a published paper (Oelofse et al. 2013) on ‘The implications of phasing out conventional nutrient supply in organic agriculture: Denmark as a case’. 

Recirculation of nutrients from urban waste is one of the core ideas behind organic farming, but at the same time it is controversial, mainly because it is seen as a risk of polluting the soil and the organic food products. To analyse opinions on this dilemma, we have performed qualitative interviews with groups of organic farmers and consumers. We believe that the results from these interviews give us a detailed and valuable material for analysis of which factors affect the attitudes of consumers and organic farmers towards accepting the available alternatives to the use of conventional animal manure in organic farming. During 2013 the results have been presented at meetings, e.g. at Organic Denmark, and used in the discussion of this recycling of urban waste sources as alternative nutrient sources in organic farming.

During 2012 and 2013 we have conducted two field trials each year, combining combined different compost types and spring wheat cultivars. The field trials are multi-purpose trials, looking for compost effects on wheat growth, nutrient uptake, yield and quality, demonstration trials for presenting the RoCo project and the topics we work with, and for supplying material for the studies of baking quality of wheat and compost effects on this. We have selected fields on organic plant production farms, where we expect relatively low nutrient availability, to mimic the situation which is likely to be common in the future after the use of conventional animal manure has ceased. The experiments have been located at two different parts of the country (Jutland and Zealand) in order to allow more people to visit them on open field days. 

The effects of compost types on yield have been small increases in yield and gluten content. Interactions are indicated in the results, e.g. the cultivar “Taifun” which have showed superior root growth also seemed to compete better with weeds and increase its gluten content more than other cultivars when fertilized with compost. Analysis of nutrient uptake (a broad range of nutrients and heavy metals analysed) at different growth stages show significant cultivar differences but there is no indication that the compost fertilizations have led to increased heavy metal uptake during vegetative growth, we are still awaiting results from analysis of the harvested grain.

Experiments with baking quality of the wheat from the 2012 field experiment have shown very interesting results where a range of quality parameters evaluated by a taste panel were affected by the types of compost used for fertilizing the wheat cultivars. In both years the compost gave small increases in yield, N content and gluten content in the wheat, so we may expect to see similar results when baking tests are made with wheat samples from the 2013 harvest; this will be made in early 2014.

Another line of work is using natural additives for improving the baking result. We have done initial studies with addition of rosehip (adding vitamin C) and malt (adding amylase), both of which have potential improving the baking result. This work will be finished and published during 2014, where it is also planned to make a consumer survey on the consumer attitudes towards quality of organic bread products.  

A final activity in the project is to develop the advisory work on the use of manures, green manures and crop rotation for nutrient management in organic farming. A core aspect of this work is to introduce the Dutch NDICEA model as a tool to analyse and develop manuring and crop rotation on organic farms. During 2013 we have made Danish information material about the model, and we have been teaching farmers and advisors in how to use the model and to interpret its output.

2012: Progress and activities: 

During 2012 we have conducted two field trials where we have combined different
compost types with different spring wheat cultivars, and we will repeat this in 2013, maybe with some adjustments based on other results obtained until now on root growth and other factors. The field trials are multi-purpose trials, looking for compost effects on wheat growth, yield and quality, demonstration trials for presenting the RoCo project and the topics we work with, and for supplying material for the studies of baking quality of wheat and compost effects on this.

We have selected fields on organic plant production farms, where we expect relatively low nutrient availability, to mimic the situation which is likely to be common in the future after the use of conventional animal manure has ceased. The experiments have been located at two different parts of the country (Jutland and Zealand) in order to allow more people to visit them on open field days.

The effects of compost types on yield have been small increases in yield and gluten content. Interactions are indicated in the results, e.g. the cultivar “Taifun” which have showed superior root growth also seemed to compete better with weeds and increase its gluten content more than other cultivars when fertilized with compost.

Experiments with baking quality of the wheat from the field experiments have just started and results are expected in early 2013. The indicated effects of composts on gluten content make us hope for interesting results of baking tests.

Another line of work is using natural additives for improving the baking result. We have done initial studies with addition of rosehip (adding vitamin C) and malt (adding amylase) which both have the potential for improving the baking result. This work will continue in 2013 in cooperation with bread baking companies. Such developments may help us produce good bread from organic wheat also in a future situation where, manure from conventional farms cannot be used to raise the protein content.

A final activity in the project is to develop the advisory work on the use of manures, green manures and crop rotation for nutrient management in organic farming. A core aspect of this work is to introduce the Dutch NDICEA model as a tool to analyze and develop manuring and crop rotation on organic farms. This work is made in cooperation with other projects working on adaptation of the NDICEA model for Danish conditions and Danish language. During 2012 we have worked on adapting the model for use in Denmark, promotion for organic vegetable producers and scenario simulations with the model focussing on
cover crops and compost, preparing for further extension for farmers and farm advisors during 2013.

2011: Progress and activities:

A core activity is to study cultivar variation in root growth. 
The first study of variation among spring wheat cultivars in root growth has been conducted. We have developed a system where the plants are grown in transparent tubes allowing us to follow and quantify their root growth. Plants are established close to one side of the tube, making the horizontal distance from the plant to the different parts of the tube surface variable. We have chosen a number of spring wheat cultivars including currently grown cultivars, older cultivars breed c. 50 years ago, and cultivars of spelt and emmer. In this way we make sure that we include a great genetic variability improving our chance to find important differences in root growth.

By comparing new and old cultivars we also get the chance to evaluate whether modern breeding performed at high nutrient availa-bility has led to selection of cultivars with reduced ability to perform well at low nutrient availability. 

Preliminary evaluation indicates that there are differences in root system exploration of the soil, including differences in branching patterns. The main roots growing from the seeds and the plant basis determine the overall spread of the root system, but the formation of second order lateral roots also strongly affect how fast the root system establish contact with available nutrients in the soil. In the experiment there appeared to be significant cultivar differences in branching, in timing of the appearance of secondary root branching and in the length and density of the root branches along the main root axes. Experiments with spring wheat continues in 2012. Similar experiments with onion cultivars are also planned for the spring of 2012 and with lettuce cultivars for later during 2012.

The results from these studies will be used as a basis for selecting cultivars to be grown in the main field trials, as well as for studies looking at cultivar differences in the ability to utilize nutrients from less available nutrient sources such as compost.

In the RoCo project we also work with recirculation of plant nutrients from different types of urban waste to be used as nutrient sources for organic farming, and we have initiated production of different types of compost based on urban waste sources.

We are working with urban waste sources which are relatively unproblematic to work with, as well as types such as sewage sludge which are more problematic and not presently allowed as fertilizers in organic farming. In an analysis of the potentially available sources of nutrients from urban waste we have found that they are presently large compared to the need for nutrient import for organic farming in Denmark. However, this is based on the current situation where only around 7% of the Danish farm land is grown organically. Further, this is only true if also the more problematic sources are used. If we only use source separated household waste and waste from parks and gardens, urban waste will only supply a quite limited part of the nutrients needed for organic farming.

We will conduct an interview study including consumers as well as organic farmers, investigating their opinions towards recirculation of urban waste. The goal is to understand which reasons are given, and especially what re-sons are given for being concerned about recirculation. We have now developed a questionnaire for this study, where we attempt to include arguments in favour as well as arguments against recirculation. Later during the project, the results will be used for discus-sions concerning future development of regulation on recirculation, e.g. on meetings with members of Organic Denmark. 

During 2012 and 2013 we will conduct multi purpose field trials with combinations of compost types and wheat cultivars with different root growth characteristics. One objective is to test the effect of compost types and the possible interactions with wheat cultivars with dif-ferent root growth characteristics. Another main objective is to use the trials for demonstration of the project and its main areas of study, and finally we will produce wheat samples for studies of baking quality of wheat and possible effects of compost application on this. We have selected fields on organic plant production farms, where we expect relatively low nutrient availability, and established green manure crops in the autumn of 2011 to secure a reasonable level of nitrogen for the wheat crops in 2012.

Experiments with baking quality of wheat start during 2012. We will investigate pos-sible interactions in the effect of cultivars and compost fertilization on baking quality, and we will study the baking process in itself. For this we will cooperate with baking companies, to study how the baking process can be developed and whether natural additives can be used to improve the baking result when making bread from organically produced wheat having a protein content below the ideal level for good baking quality. 

A final activity in the project is to develop the advisory work on the use of manures, green manures and crop rotation for nutrient management in organic farming. A core aspect of this work is to introduce the Dutch NDICEA model as a tool to analyze and develop manuring and crop rotation on organic farms. This work is made in cooperation with other projects work is already ongoing on adaptation of the NDICEA model for Danish conditions, the RoCo activities on this area will start during 2012. 

Project leader

Kristian Thorup-Kristensen
KU-LIFE
Højbakkegårds Allé 13
DK-2630  Tåstrup

Tel: (+45) 35 33 22 16
E-mail: ktk@life.ku.dk 

Find publications from the project in Organic Eprints