LATVIA UNIVERSITY OF AGRICULTURE - Latvijas ...

IMPACT OF SLURRY APPLICATION METHOD ON SWARDYIELD AND N AND K LEACHING FROM GRASSLANDTampere Mailiis4,03,5SpreadInjection3,02,5Leaching, g K m -22,01,51,00,50,0-0,560 120 18060 120 18060 120 180N rate, kg ha -1N rate, kg ha -1N rate, kg ha -1Grasses + white cloverGrassesGrasses + lucerneFigure 3. Average K leaching during vegetation period in two slurry application methods(average results of three years).in grasses sward, the influence was less in grasses +lucerne sward and it was absent in grasses + whiteclover sward. Legumes do not tolerate high N rates.When used N rates are high, the importance oflegumes in the sward declines remarkably.The reason why K leaching in grasses + whiteclover sward remained constant with increased N ratecould be that K leaching was very small already atthe lowest rate N60. Increased N rate brought downthe importance of white clover in the sward and its Nsupply. The amount of N brought in the soil by slurrywas not quantitatively higher than the amount of Nbrought to soil by white clover.K leaching may also be affected by the nutrientcontent of the slurry, which does not correspond toplants needs. In our experiment N:P:K ratio was1:0.20-0.22:0.62-0.75, while the optimal nutrientratio recommended in the literature for grasses is1:0.22:0.62 (Viiralt, 2007). It has to be considered thatwhen applying slurry in the year of fertilization, thesward yield is mainly influenced by the ammoniumnitrogen in the slurry. In our study the importance ofthe ammonium nitrogen in the slurry was 39.5-58.2%.Therefore, when giving N rate based on ammoniumnitrogen, plants may receive more K than plants areable to consume.Conclusions1. Our results support the hypothesis that slurryinjection results in less N leaching. N leachingwas significantly smaller with slurry injectionin grasses + white clover and grasses + lucernesward. Our results indicate that N and K leachingdepends on sward yield. It was most noticeable ingrasses sward where with higher yield leachingdecreased.2. From our results it can be concluded that swardyields and K leaching did not depend statisticallyon slurry application method. According to ourresults slurry injection is potentially beneficialonly in grasses sward when used N rates are above120 kg ha -1 yr -1 . Slurry injection may have negativeinfluence on the distribution of white clover in thesward, thus resulting in lower sward yield.3. We consider that K leaching may also be influencedby the N: K ratio in the slurry. In our experiment itcould have been too narrow as plants did not haveenough N to assimilate K.AcknowledgementsThe study was supported by the Estonian Ministryof Agriculture and the Estonian Ministry of Educationand Research (SF 0170052s08).42 Research for Rural Development 2012