INFLUENCES OF BIO-DYNAMIC AND ORGANIC TREATMENTS ON YIELD AND QUALITY OF WHEAT AND POTATOES: THE WAY TO APPLIED ALLELOPATHY?

INFLUENCES OF BIO-DYNAMIC AND ORGANIC TREATMENTS ON YIELD AND QUALITY OF WHEAT...

Results of the First Year of a Medium Term Systems Comparison Research

G. Deffune1, A.M. Scofield2, H.C. Lee2, J.M. Lopez-Real2 and P. Šimünek3

1 geraldo.deffune@uniube.br - Researcher and Lecturer at the Universidade de Uberaba (MG), Ph.D. at Wye College sponsored by CNPQ - the Brazilian National Research Council.

2 Senior Lecturers at Wye College - Department of Agricultural Sciences of Imperial College, University of London, Wye, Ashford, Kent TN25 5AH, U.K.

3 Ph.D. - Department of Food Technology, Mendel University, Brno, Czech Republic.

*Originally published in the Proceedings of the 4th ESA (European Society for Agronomy) Congress, Veldhoven, The Netherlands; p. 536-537.

Introduction

Many organic substances have allelopathic effects in agroecosystems (Rice, 1984). The so-called biodynamic (BD) preparations were the first set of plant extracts and solutions widely used in what can be regarded as applied allelopathy in farming systems (Deffune, 1990). This method has been successfully used by Brazilian farmers (Pio et al, 1984) and holds great potential regarding biodiversity, for the discovery of new sources of active principles or ingredients (Almeida, 1988). A PhD research project was carried forward between 1993 and 1998 to investigate these effects and techniques.

Spring wheat (T. aestivum, var. Canon) and potatoes (S. tuberosum, vars. Cara and Pentland Crown), two of the world’s most important staple foods, were chosen as test crops in field trials also for being complementary in a polar sense – one a Old World Monocotyledon ear producer; the other a New World Dicotyledon tuber producer.

A mixed green manure rotation with rye (Secale cereale) plus vetch (Vicia sativa) was added to the field trials to simulate an organic farming system. Field trials were supplemented by laboratory and glasshouse experiments.

Crop yield and health, nutritional and keeping qualities of produce as well as soil nitrogen content levels were the parameters evaluated.

Methods

The experimental design was based on randomized complete block blind experiments, with secret codes for both compost, soil and spray treatments: A=control, A+= chemical fertilizer and foliar spray, B&C=blind BD & Organic, using 60 T ha-1 of standardized compost treated with preparation sets and sprays blind-labelled B&C.

Double-blind re-coding of samples was used before quality assessments of both wheat and potatoes. Successive cropping seasons (1993-95) in the same plots, were used to check for cumulative effects, with crops cultivated in spring/summer of 1993-95 and rotation with rye/vetch mixture for green manure and weed control (1994). The biomass was left as mulch in B&C plots and removed from the control plots. The treatments were Bio-dynamic preparations applied as follows (Koepf et al., 1976):

1. Field sprays - used in sequence and additional to compost treatments: P500 soil spray (17 ml.m-2), fermented cow manure, stir-diluted 3.3 g.l-1.

P501 plant spray (138 ml.m-2), silica dynamized 83 mg.l-1(5g per 60 l).

Nettle water 2% Urtica dioica (planta tota) 138 ml.m-2; 1st month

Equisetum arvense decoction 1% stir-diluted, 138 ml.m-2.

Kieselguhr (diatomaceous earth) 0.5% stir-diluted, 138 ml.m-2.

2. BD Compost Preparations were blind-added to a Controlled Composting process - additives P502 to P507 (200 mg.m-3): Achilea millefolium - flowers, Matricaria recutita - flowers, Urtica dioicaplanta tota, Quercus robur - bark, Taraxacum officinale - flowers and Valeriana officinalis - flowers' liquid extract. Both treated and untreated compost heaps did not significantly differ in NPK contents (e.g.; average of 2,5% total N) in three batches/years .

3. Mixed spray (blind coded) for tilled soil manured with untreated standard compost in 1993 (1st year) trials: P500 (200g per 60 l) + P502-P506 (4g per 60 l = 6.7 mg.l-1) + P507 (4ml per 60 l).

4. In the second year (1994), while the first year plots were under rye (Secale cereale) plus vetch (Vicia sativa) green manure rotations, two additional field trials of wheat and potatoes were set under split-plot designs between the same soil treatments and five sprays: 10% solutions of Urtica dioica, composts B and C; a mimic concentration Murashige & Skoog salts nutrient solution and a water control.

5. In the third year the successive cropping plots were re-planted with wheat & potatoes under splitplot designs between the four soil treatments and two blind-sprays, with and without P501 silica.

Plates 1 and 2 illustrate aspects of the field plots.

Plate 1. South-western view of wheat trial, showing field plots randomly treated with compost. 2

Plate 2. View of the same wheat trial, showing plants in flowering stage.

Plate 3. View of a potato trial with stinging-nettle 2% preparation spraying. 3

Results

Contrasts of interest (Pearce, 1992) show statistically significant differences already found in the first year (1993) of experiments, as follows:

1.Wheat

The Agrochemical system produced higher grain yields than the average of the Organic & BD systems (A+ vs B&C*), while the latter also significantly increased yields in relation to the Control (A vs B&C*; Figure 1).

Figure 1. Spring Wheat'93 "Canon" - Yields per hectare of grain with 14% moisture content in blind RCB field trial, under four systems: A (nil), A+ (Ammonium Nitrate, 125 KgN/ha), B & C = blind Organic & Biodynamic (60T/ha FYM compost).

On the other hand, the Agrochemical system resulted in lower quality than all others in terms of Thousand Grain Weight (TGW**, Figure 2) and baking properties (HFN*- Hagberg Falling Number; Plate 4 and Figure 3).

Control(A) Nitram(A+) Organic(B) Biodynamic(C) Systems

Contrasts:

Figure 2. Spring Wheat'93 (variety Canon) - Mean Thousand Grain Weight (TGW) comparing four treatment systems in double-blind RCB field trial (same as Fig. 1).

The BD treatment showed optimal HFN*(249.83; Figure 3) with a lower phosphorus** content than the Organic (the highest in P), while other element levels like Ca, K, Na, NO3 and Ash did not vary significantly in the grain.

Plate 4. Illustrated poster of the Hagberg Falling Number method for flour baking quality evaluation

Control(A) Nitram(A+) Organic(B) Biodynamic(C) Systems

Figure 3: Baking quality of spring wheat "Canon", using Hagberg Falling Number (inverse factor of alpha-amylase activity), comparing four treatment systems in double-blind RCB 1993 field trials.

2. Potatoes

While the treatment systems produced some significantly different mean fresh yields, dry weight yields (Figure 4) did not differ between the systems A+ vs B&C and NPK treated potatoes had the lowest dry matter content*** (Figure 5).

Figure 4. Potato'93 – Dry Yield means. Split plot RCB field trial with two varieties (Cara &

Pentland Crown) and four systems: A = nil, A+ = NPK (670 Kg/ha of 15-15-20), B & C = blind Organic & Biodynamic (60 T/ha of compost).

Control(A) Nitram(A+) Organic(B) Biodynamic(C) Systems

H F No

HFN scores: below 150 = sticky bread; between 200 & 300 = acceptable; 300 plus = dry bread.

Control(A) NPK(A+) Organic(B) Biodynamic(C) Systems

Fresh Yield (T.Ha)

Cara Pentland Crown

Means marked with the same letters (a,b,c,d) do not differ significantly at the 5% level

Contrasts:

Figure 5. Potato'93 – Dry matter contents of samples in the same experiment.

The Organic and Biodynamic systems (B&C) have also shown better conservation* (less "spraing" and tissue browning after a 6 month storage period (Figure 6). In the B vs C comparison, B (organic) had a higher amount of "chats"* (tubers smaller than 40mm) than C (BD). There were overall differences between treatment systems* and varieties***.

Figure 6. Potato quality evaluated by tissue browning scores after a six month storage period.

Scores 0-10 are equivalent to 0-100% (one score unit = 10%) of affected tuber crosssection area of two potato varieties under four treatment systems in double-blind RCB 1993 field trials.

The Agrochemical system resulted in much higher soil NO3 levels through and after the cropping season for both wheat and potato plots (Figure 7 and 8), which did not reflect in proportionally higher yields and is undesirable for soil water quality.

Control(A) NPK(A+) Organic(B) Biodynamic(C) Systems

Browning Scores

Cara Pentland Crown

Control(A) NPK(A+) Organic(B) Biodynamic(C) Systems

DM% Cara Pentland Crown

Figure 7. Soil Nitrate means in 24 plots under four soil treatments in medium term Wheat Trial: three sampling dates during cropping season 1993, plus one final sampling in 1995, at the end of the experiment (same as Fig. 1).

Figure 8. Soil Nitrate means in 24 main plots under four soil treatments in medium term Potato Trial: three sampling dates during potato growing season in 1993, one after potato harvest in 1995, at the end of the whole experiment (same as Fig. 4).

Conclusions

Significant quality differences between Bio-dynamic and Organic treatments indicate the presence of allelopathic stimulation by the BD preparations, showing the way to detect these subtle effects

Control(A) Nitram(A+) Organic(B) Biodynamic(C)

Contrasts:

Green Manure rotation interval

Control(A) NPK(A+) Organic(B) Biodynamic(C) s.e.d.= 0.385s.e.d.= 0.641s.e.d.= 0.0684s.e.d.= 0.454

May & June'93: p(A+ vs A,B,C)< 0.001***; August'93: p(A+ vs A,B,C)= 0.024*Contrasts: November'95: p(A+ vs A,B,C)= 0.019*

Green Manure rotation interval

(Smith, 1993). Much higher soil nitrate levels in the positive control "A+" plots did not increase proportionally the yields, but significantly correlate to lower quality in both wheat and potatoes. Results show the possibility to improve crop yield and quality of produce, through simple and environmentally adequate techniques, directly available to farmers (Reganold et al., 1993).

References Almeida, F.S. (1988). A alelopatia e as plantas. Circular nº53, IAPAR, Paraná, Brazil, 60 p. Deffune, G. 1990. M.Sc. Dissertation, Wye College, 1-28. Koepf, H.H. et al., 1976. Bio-dynamic Agriculture: an introduction, 4: 206-224. Pearce, S.C. 1992. Experimental Agriculture 28: 245-253. Pio, D.M. et al.,1984. Lebendige Erde 6: 269-274. Reganold, J.P. et al., 1993. Science 260: 344-349. Rice, E.L. 1984. Allelopathy, Academic Press, Orlando, 10: 266-291 Smith, R.L. 1993. Journal of Applied Nutrition, 45(1): 35-39.

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