Does Lupinus angustifolius L. need sulfur fertilization under central European conditions?

Abstract

In order to answer the question of whether narrow-leaf lupin (Lupinus angustifolius L.) needs sulfur (S) fertilization under central European conditions, field trials were carried out at several sites in Germany on long-term (> 10 years) organically cultivated arable land from 2012 to 2014. The effect of S-containing fertilizers kieserite, gypsum, epsom salt, and elemental sulfur on S accumulation, yield, yield structure, and nitrogen (N) accumulation in narrow leaf lupin as well as the recovery of fertilized S was investigated. Under the given conditions, the fertilization did not influence seed yields. The S accumulation in shoots ranged from 11.8 kg ha −1 to 14.1 kg ha −1 . The bulk of the absorbed S was accumulated in the straw (average S harvest index: 0.40). The N : S ratio in the youngest open leaf at BBCH 60–65 was about 20 and the corresponding S concentration was 0.24% in the leaf dry mass. The apparent recovery efficiency of S (RE) of kieserite, gypsum, and epsom salt, whose S form is generally plant-available, was low with 4.0%, –2.1%, and 6.6%, respectively. The S requirement of the lupin was obviously completely filled by plant-available S from the soil as well as atmospheric S deposition in all tested environments. Application of kieserite, gypsum, and epsom salt resulted in a partially significant increase in S concentration of seeds and straw, and also partly significantly narrowed the N : S ratios in the plants but did not increase yield. Application of elemental S did not lead to an increase in plant S concentration in the year of application.