Experimental factors and levels
A - Organic fertilization
a1 30 t/ha farmyard manure every 2nd year (fall) to maize
a2 20 t/ha farmyard manure every 2nd year (fall) to maize
a3 without
B - Mineral fertilization
b1 NPK
b2 NP
b3 NK
b4 N
b5 PK
b6 without
Further treatments
Liming
Stripe 1 limed
Stripe 2 not limed
Cultivation of legumes
Stripe 7 without legumes
Stripe 8 with legumes (since 1970: lucerne every 7th and 8th year)
Organic fertilization: Farmyard manure is applied as an organic fertilizer in 3 stages: every two years 30 t/ha (since 1906), 20 t/ha and no farmyard manure. The quantities refer to the fresh matter. The manure is spread on the crop stubble around mid-October. A local agricultural company delivers it in spring from a cattle barn, then it is placed in a heap on a manure plate and stored for at least half a year. Since 2019 it has been covered with a tarpaulin during this storage period. Before spreading the manure, a sample is taken and analysed for its dry matter content as well as Corg, N, P, K, Ca and Mg in the DM to contribute to the long-standing studies on these parameters. Protective strips are placed between the manure blocks to reduce the risk of manure spreading between the blocks during tillage.
Mineral fertilization: The mineral fertilization has 6 levels: NPK, NP, NK, N, PK and without any mineral fertilizer. These mineral fertilizer combinations have not been changed since 1902, but the amount of mineral fertilization was altered over the decades. Since the launch of the experiment the amount of fertilizer has been dependent on and adjusted according to the amount of farmyard manure applied as well as on crop type and variety. Some field stripes received different forms of nitrogen (from 1924 to 1977) in order to investigate the effect of physiologically acidic or basic nitrogen fertilizers on soil and plants: SH 3 ammonium sulphate, SH 4 calcium nitrate, SH 5 ammonium sulphate, SH 6 sodium nitrate.
Liming: In 1924, liming (30 dt of lime marl every 4 years in spring before laying the potatoes) was introduced on SH 1. Since SH 1 and 2 always bear the same crop, the effect of liming on soil and plant can be studied by comparing the two field stripes of the field.
Legumes: In 1926, legumes were introduced into the crop rotation on SH 8. Since 1970, lucerne has been in every 7th and 8th year (corresponding to a share of 25 %), sown after harvesting the preceding crop, winter wheat, in August. Apart from the lucerne, SH 7 bears the same crop as SH 8, so that the effect of lucerne on soil and plant can be studied by comparing the two field stripes.