Technique of green mulch spreading

Summary

Finland’s policy of subsidising the conversion to organic production precipitated the rapid growth of organic farming in the 1990’s. As a consequence, many stockless farms encountered the problems of nitrogen deficit, poor grain quality, and weed control. Since the spreading of green mulch on cash crops is very common especially in tropical agriculture, organic fertilisers like green mulch may be an alternative that would compensate for the prohibition on the use of mineral N-fertilisers. However, one problem is that presently there is no appropriate technique available to substitute for the strenuous handwork of spreading green mulch.
The main subject of this research report is the technique of green mulch spreading. Between 1994 and 1997, a green mulch spreading prototype was developed and tested. An evaluation of four different spreading techniques, including the prototype, revealed that the optimal technique was still not found and that none of the techniques considered in this report achieved the quality of hand work. The prototype did, however, allow us to perform experiments using different green mulch crops and/or mixtures of green mulch crops to a greater extent.
From 1996-1999 experiments were conducted using the following crops as green mulch: rye Secale cereale, red clover Trifolium pratense, alfalfa Medicago sativa, timothy Phleum pratense, meadow fescue Festuca pratensis, reed canary grass Phalaris arundinaceae and different mixtures of them. Green mulch was applied to following cash crops: Cabbage Brassica oleracea var. capitata, burdock Arctium lappa, valerian Valeriana, peppermint Mentha piperita, anise hyssop Agastache foeniculum, stinging nettle Urtica dioica, spring wheat Triticum aestivum, and spring barley Hordeum vulgare.
The experiments produced the following results: 1) The fertilising effect of green mulch application is ambiguous. 2) Weather conditions influence both the mineralisation and the quantity of green mulch, the timing, and the frequency of mulching. 3) Persisting green mulch cover can be achieved using rye or reed canary grass. 4) An area ratio of 4 : 1 green mulch crop : cash crop seems to be sufficient for weed control. 5) With the exception of wet young red clover, all of the green mulch crops used were suitable for the prototype machine.
On condition that the weather is suitable, the strip intercropping technique in combination with the row mulching machine of Fischer Ltd. is presently the best available green mulch spreading-technique. Only zero traffic technology such as gantry technology offers perfect green mulch spreading which is independent from weather and soil conditions. However, even improved spreading technique does not solve the other problem, which is caused by weather conditions: Uncertain growth and mineralisation of green mulch. This is mainly a problem in North European countries where conditions are the opposite of those in tropical areas. In tropical areas, temperature and humidity always ensure both, vigorous growth and rapid mineralisation.
In any event, a legume-rich crop rotation and organic manure from livestock would be the better alternative for fertilisation in organic farming under North European conditions. Another alternative is the use of milled seeds of legumes, hornmeal or cake of Ricinus communis. For these materials, traditional fertilising machinery is available. The application of these organic fertilisers is not weather dependent and they can be produced and purchased far from the location of application.
The worldwide application of green mulch is essential for a sustainable agriculture. Although in most tropical countries spreading is still done by hand, the mechanisation of green mulch spreading will gain increasing importance in the near future.
TABLE OF CONTENT
Acknowledgements 7
1. Introduction 8
2. State of knowledge on green mulch research 8
2.1 Green mulch crops 8
2.2 Green mulch effects 9
2.2.1 Mineralisation and fertilisation 9
2.2.2 Weed control 10
2.2.3 Pest control 11
2.2.4 Soil temperature and soil moisture 11
2.2.5 Soil fertility and N-losses 11
3. State of green mulch technology 12
3.1 Machines for grassland 12
3.2 Machines for berries and fruit trees 14
3.3 Machines for cereals 16
3.4 Machines for maize 16
3.5 Machines for potato 17
4. Design of a prototype machine for green mulch spreading in row crops 17
4.1 Knowledge base when starting 1994 17
4.2 Design and testing 18
4.3 Conclusions 21
5. Evaluation of green mulch spreading techniques in row crops 24
5.1 Techniques of green mulch spreading 24
5.1.1 Technique A: Modified manure spreader 24
5.1.2 Technique B: Modified flail 24
5.1.3 Technique C: Combination of modified manure spreader and modified flail 25
5.1.4 Technique D: Modified disc mower 25
5.2 Evaluation methods 25
5.2.1 Calculation of working time 26
5.2.2 Rating of process criteria 27
5.2.3 Cost calculation 28
5.3 Results and discussion 29
5.4 Conclusions 30
6. Experiments with green mulch 30
6.1 Experiments in 1996 with cabbage 30
6.1.1 Practical tests using the green mulch prototype machine 30
6.1.1.1 Material and methods 30
6.1.1.2 Results 41
6.1.1.3 Conclusions 43
6.1.2 Field experiments spreading green mulch by hand 43
6.1.2.1 Material and methods 43
6.1.2.2 Results 44
6.1.2.3 Conclusions 46
6.2 Experiments in 1997 with beetroot 47
6.2.1 Material and methods 47
6.2.3 Results 47
6.2.3 Conclusions 49
6.3 Experiments with spring cereals in 1998 and 1999 49
6.3.1 Material and methods 49
6.3.1.1 Design and operations in the field experiment 50
6.3.1.2 Fertilising techniques 51
6.3.1.3 Plant and soil analysis 52
6.3.1.4 Statistical analysis 52
6.3.1.5 Calculation of N-balance 53
6.3.2 Results and discussion 53
6.3.3 Conclusions 61
7. Conclusion 61
References 63