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Effects of farmyard manure compost and biodynamic preparations

Long-term trial at IBDF Darmstadt (since 1980)

1980-1984 Product quality

First period (research focus: Food quality)

Reference: ABELE (1987)

Extinction of potato extract

Parameters:

Chemical parameters: total N, nitrate, protein N, free amino acids, P, K, Na, Mg, sugar fractions, starch, organic acids, vitamin C, carotene, solanene
Physical parameters: tissue strength of potato tubers
Biochemical parameters: enzyme activities, respiration, aroma patterns
Microbiological / biochemical parameters: in storage experiments under optimal conditions: intensity of microbial attack, dry matter loss, CO₂development; in degradation tests with grated samples: intensity of microbial attack, dry matter loss, CO₂ development during incubation, darkening (extinction) of potato extract

Summary of results:

Minerally fertilized vegetables had much higher nitrate contents than the organically fertilized samples (see below).

Under optimal storage conditions, the durability of products showed only small differences.

Under stress conditions (as regards temperature, humidity, chopping up), however, much clearer differences occurred in terms of microbial attack and degradation and in darkening of potato extract (see figure above), mostly in favour of lower instead of higher fertilization levels, in favour of manure compared to mineral fertilization and in favour of treatments with biodynamic preparations (see examples below).

**Nitrate content (ppm FM) in vegetables with organic and mineral fertilization, average of the years 1981-84**
	CM	CMBD	MIN	low	medium	high
Carrots	119 a	109 a	199 b	90 a	149 b	188 c
Beetroot	973 a	962 a	1315 b	800 a	1087 b	1363 c
Potatoes	99 a	95 a	162 b	94 a	122 ab	140 b
Mean values of a factor with different letters are significantly different (p<0.05); calculated by Raupp (1997) with values of Abele (1987).

Nitrate contents in organically fertilized vegetables were uniformly much lower than in the mineral treatments.
Maximum contents in all crops and over all years were found to be higher with mineral fertilization. Higher levels of fertilization caused nitrate accumulation in the products. (Yields were approximately the same with organic and mineral fertilization.) Click for more information on nitrate in food.

Nitrate contents in carrots in 4 years with mineral (MIN)
and organic (CM; CMBD) fertilization, at 3 fertilization
intensities (1,2,3).

The example of carrots: Lower nitrate contents with manure fertilization (CM, CMBD), even at the highest fertilization intensity.
Rising amounts of mineral fertilizer increased nitrate contents to a greater degree than rising manure application. Despite some variation of contents over the years, the advantage of organic fertilization remains evident.

	MIN	CM	CMBD
high
medium
low

Best durability of carrots with manure fertilization with biodynamic preparations (CMBD) at low fertilization intensity (box at the botom right).
The carrots were stored from December 1981 to February 1982 under non-optimal conditions (25°C, close to 100% rel. humidity). With the high level of mineral fertilization the carrots were almost completely decomposed (box at the top left).

Fungus growth on chopped beetroot most extensive on minerally fertilized samples.
The picture shows each of the 9 treatments in 5 lab replicates after incubation at 30°C. Only at the low fertilization level were minerally fertilized samples as less attacked as those of manure treatments.

**Rottenness, fungus growth, dry matter loss and CO₂-development during incubation; nd = no difference**
	Carrots	Beetroot	Potatoes
Rot, fungus growth	MIN > CM >= CMBD (1981+83)	MIN > CM(BD) (1981)	MIN > CM(BD) (1981)
DM loss	MIN > CM(BD) (1981+83)	nd (1983)	nd (1983)
CO₂-development	MIN = CM >= CMBD (83) nd (84)	MIN > CM(BD) (83) MIN < CM(BD) (84)	nd (83) nd (84)
Summarized by Raupp (1997) with data of Abele (1987)

The results of degradation tests can not always be reproduced exactly and interpreted easily.
Probably because of poorly standardized test conditions, different results may be obtained with the same crop in different years or with various crops in one year. As a rule, the microbial infestation of chopped samples is well reproduced, and organically fertilized vegetables were wearkerly attacked.

A summary of results and an evaluation of the pros and cons of degradation tests is published in: RAUPP, J. (1998): Examination of some microbiological and biochemical parameters and tests of product quality used in a long-term fertilization trial. Amer. J. Alternative Agric. 13, 138-144

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