II. MARCO TEÓRICO
2.7. La alegoría
Skriveri-1, Aizkraukle distr., LV 5126, Latvia
e-mail: [email protected]; [email protected]; [email protected]
Abstract
During the years 2003 - 2004 the Research Institute of Agriculture of the Agency of the Latvia University of Agriculture (LUA) established experiments in organic farming fields. The aim of these experiments was to clarify most suitable legume and forage grass varieties and their mixtures for seed production under organic farming conditions.
The test results proved the following: under unfavourable weather conditions lucerne variety ‘Skriveru’ gave the seed yield 79 kg ha-1. The new meadow fescue variety ‘Silva’ produced
seed 312 kg ha-1. The hybrid ryegrass ‘Saikava’ grown in the sowing year side by side with
annual lupine ‘Danko’ presented the seed yield of 581 kg ha-1. Better yields were obtained
when forage grasses were grown in mixture with legumes: red clover ‘Skriveru agrais’+ timothy ‘Teicis’- 201 kg ha-1, and alsike clover ‘Menta’+ timothy ‘Teicis’- 244 kg ha-1. In
pure sowings all these varieties produced relatively lower yields.
Key words: organic farming, seed production, forage grasses, legumes, varieties
Introduction
In Latvia, the area devoted to organic farming cover about 1.5 % of total agricultural land. In 2003, there were 550 organic farming enterprises managing 24 480 ha of land. Organic farming is gaining popularity both in Latvia and the world.
In many areas of Europe numerous research projects and reviews on agronomic and environmental consequences of organic agriculture were carried out. In the Baltic states, much of research has not been done in the field of organic farming, but the high importance of research is clearly recognised by several institutions dealing with organic farming. It is especially needed to find out appropriate crop rotation and varieties for this farming (Geherman and Ellermae, 2002).
Legumes as a source of cheap biologically fixed nitrogen are very important both in organic and conventional farms (Baars and Veltman, 2000).
Legumes fixing atmospheric nitrogen completely supply themselves with this plant food element and also contribute to companion forage grasses (Slepetis, 2003).
Latvia and other countries of Europe miss experience and scientific research on forage grasses and legume seeds in organic farming fields.
The average seed yield of forage grasses and legumes produced in conventional farming is about 500 kg ha-1 and 100 kg ha-1 respectively with large variations between production
years. It depends on agro climatic conditions of the year, and soil fertility. Experiments conducted on forage grass seed production for organic farming purposes are not sufficient enough.
The objective of this paper was to analyse the forage grass seed yields produced without using mineral fertilizers, but applying the legume effect to fix biologic nitrogen.
Materials and methods
Research Institute of Agriculture in Skriveri started to test more suitable varieties. The tests were carried out in a certified organic farming field in the spring of 2003.
The soil at the site is sandy loam with organic matter content 3.5 %, pHKCl 5.8, K2O - 155 mg
kg-1, P
2O5 - 84.4 mg kg-1.
The following varieties of legumes were estimated: 2 varieties of early ripening red clover ‘Skriveru agrais’ and ‘Arija’, mid-early ripening red clover ‘Dizstende’, alsike clover ‘Menta,’ and lucerne ‘Skriveru’. The seed rate for all legumes was 8.0 kg ha-1. Two forage grasses were estimated in pure sowing: cocksfoot ‘Priekulu 30’ and meadow fescue ‘Silva’, the seed rate was 15.0 kg ha-1, as well as 5 mixtures of forage grasses and legumes (two components) were used: red clover ‘Skriveru agrais’+ timothy ‘Teicis’ (5+5 kg ha-1), alsike clover ‘Menta’+ timothy ‘Teicis’ (5+5 kg ha-1). Meadow fescue ‘Silva’, hybrid ryegrass ‘Saikava’ and cocksfoot ‘Priekulu 30’ were sown in mixture with annual lupine ‘Danko’. The aim of the research was to elucidate whether biologic nitrogen fixed by lupine could influence the forage grass yield and, if so, to which extent as compared to grasses grown in pure sowing.
Trials were established in randomised complete blocks in four replications. Meteorological conditions were different during experimental years. In June 2003, when trials were established, the average temperature was by 0,7 0C degree below the norm, but the amount of
precipitation made 75 % of the norm. July with average temperature 19 0C was the warmest
summer month.
During the vegetation period 2004 meteorological conditions were extremely bad. The spring was late and cold resulting in delayed plant development. In May frequent and strong spring frosts occurred: both forage grasses and legumes were injured by frost. The summer was cool and rainy. Meteorological conditions were represented by increased rainfall during flowering time of legumes and in autumn during harvesting of seeds. Both during the sowing year and the year of seed yield phenological observations were performed, and the yield calculation, too. All the variations and mixtures were sown in plots of 2.0 x 5.0 m in size in 4 replications. The preceding plant was bare fallow. Lucerne and annual lupine seeds were treated with appropriate microbial strains using nitragine produced by ‘Bioefekts’ and active microbial strains obtained from LUA Plant Biology and Protection Department collection. The seed yield was gathered at complete ripeness phase using combine ‘Sampo 130’. Data obtained were processed by a mathematical method.
Results
In the test year (2003) sprouts covered all the fields, and on July 21 they were cut down. Shortly before winter, on November 12, there were made measurements: the number of plants on one metre (Table 1).
In general, meteorological conditions during the vegetation period 2004 were extremely unfavourable for seed yield and good harvest, especially in the case of legumes. On May 13, cocksfoot grass was frozen dead, also lucerne and clover got frozen. During flowering period there was abundant rainfall, the pollination of legumes was hindered bringing low seed yields.
The varieties can present their positive effect mostly within specific environment for which this variety is developed. The field plant varieties grown under local conditions are potentially more elastic, more fruitful, and more resistant. The test data testify this as well.
Higher seed yields were obtained with a new alsike clover variety ‘Menta’, in mixture with a new timothy variety ‘Teicis’- 244 kg ha-1. Red clover ‘Skriveru agrais’ in mixture with
timothy ‘Teicis’ yielded 201 kg ha-1 of seed. In these unfavourable for seed growth
conditions pure legume sowings provided satisfactory seed yields: lucerne ‘Skriveru’ gave 179 kg ha-1, red clover ‘Dizstende’- 93 kg ha-1, red clover ‘Arija’ 87 kg ha-1. Treatments with
forage grasses sown in mixture with annual lupine ‘Danko’ and cut down during flowering phase provided significantly higher seed yields than in the case of being grown in pure sowings. The highest seed yield was presented by hybrid ryegrass ‘Saikava’- 581 kg ha-1, since it could nicely use the accumulated by annual lupine nitrogen.
Relevant seed material indicator is the seed coarseness, which is testified by the weight of 1000 seeds. The data presented in Table 1 testify that growing crop varieties in the organic farming field, the seed coarseness compared to commercial agriculture did not decline being 3.84 g for hybrid ryegrass ‘Saikava’, 2.18 - 2.34 g for red clover, and 1.82 g for lucerne.
Table 1 Evaluation and productivity of forage grasses and legumes in pure sowing and mixtures
Variety/ grass mixture Number of plants on 1 metre in autumn of sowing year Flower time in 1st year of sward use Harvest time in 1st year of sward use Seed yield, kg ha-1 RS0,05 Weight of 1000 seeds, g Lucerne ‘Skriveru’ 14 3 July 13
October
179.0 1.82
Alsike clover ‘Menta’ 34 22 June 26 August 78.0 0.80 Red clover ‘Arija’ 34 20 June 26 August 87.0 2.34 Red clover ‘Dizstende’ 32 30 June 10
September
93.0 2.18 Red clover
‘Skriveru agrais’ 32 20 June 26 August 82.0
17.0
2.20 Cocksfoot ‘Priekulu 30’ 26 19 May 3 August 16.0 14.0 1.32 Meadow fescue ‘Silva’ 48 15 June 19 July 312.0 20.7 2.08
‘Skriveru agrais’+
‘Teicis’ 28+ 26 20 June 26 August 201.0 2.18/0.4 8 ‘Menta’+ ‘Teicis’ 20+ 22 22 June 26 August 244.0
49.0
0.80/0.5 0 ‘Silva’+ annual lupine
‘Danko’ 36 15 June 19 July 387.0 20.07 1.88 Hybrid ryegrass
‘Saikava’+ Danko’ 30 22 June 03 August 581.0 3.84 ‘Priekulu 30’+ ‘Danko’ 32 19 May 13 August 24.0 14.0 1.28
Conclusions
All varieties of grasses that were grown in the test fields could also be grown in organic farming fields for seed growing needs since they did not require high fertilizer input, were more resistant to plant diseases and pests, and were satisfactory in terms of yield.
For seed production purposes most appropriate were forage grass-legume mixtures that presented higher yields.
References
Geherman, V., Ellermae, O. (2002) Nutritive status of soils, biodiversity and yielding ability of leys in Estonian conventional and organic farms. International scientific conference proceedings: Research for rural development 2002. Jelgava, Latvia.- pp. 45-49
Baars, T., Veltman, L. (2000) Adapted grass/clover mixtures for ley farming- a participatory approach to develop organic farming systems In: Soegaard K. et al. (eds). Grassland farming. Grassland Science in Europe, Vol.5, pp. 542-544.
Slepetys, J. (2003) Mixed use of red clover stands for forage and seed production. Proceedings of the 12th Symposium of the EGF: Optimal Forage Systems for Animal Production and the Environment. Pleven, Bulgaria, pp. 388-391