Comparison of composted manure and plant based organic fertilizer
Potatoes
Yield and quality of potatoes
The following results have been obtained in 2005 applying faba bean meal as plant based organic fertilizer.
Potato yield (dt ha-1) in 2005 as total and saleable amount of tubers depending upon fertilization; error bars indicate least sign. differences (p<0,05).
Both organic fertilizers gave approx. the same saleable yield of 230 dt ha-1. Higher yields could only be achieved with inorganic fertilizers and with the increased rate of farmyard manure (statistically significant only in treatment CMBD2). In contrast to earlier studies (Raupp, 2001) the biodynamic preparations did not increase potato yields, neither with manure, nor with faba bean meal.
Contents of phosphorus and potassium (% dry matter), nitrate (ppm fresh matter) and starch (ppm fresh matter) in potato tubers depending upon fertilization; mean values with different letters are statistically diferent (p<0,05).
Potato tubers fertilized with faba bean meal showed significantly lower potassium contents than the manured samples. Possibly the lower amount of potassium distributed with faba bean meal may explain this difference. The P content of the tubers have been the same with both organic fertilizers. The nitrate content, too, was fairly the same in the manure and in the faba bean treatment. The higher application rate of farmyard manure increased the P and K contents of the tubers, but not the nitrate content. The highest nitrate content has been analysed with inorganic fertilization. Application of faba bean meal caused the highest starch content.
Extinction of diluted potato extract immediately after its production (E0) and 24 hours later (E24); mean values with different letters are statistically different (p<0.05).
Darkening of potato extract at both dates (E0 and E24) was significantly weaker in the manure treatment compared to both the faba bean and the inorganic treatment. This means that the potato samples grown with plant based fertilizer have been more decomposed than the manure fertilized samples.
Conclusion:
Although no significant yield differences occurred between both organic fertilizer types, the application of faba bean meal as a fertilizer cannot be recommended, because of negative effects on potato quality.
Source:
OLTMANNS, M.; RAUPP, J. (2006): Ackerbohnenschrot im Vergleich zu Rottemist: Effekte auf Ertrag und Qualitätsparameter von Kartoffeln. Mitt. Ges. Pflanzenbauwiss. 18, 80-81
In 2004 and 2005 the study was financially supported by Bundesprogramm Ökologischer Landbau (03-OE-179).