Although grasses have dense rooting systems, nutrient uptake and productivity can be increased, and N-leaching reduced, if rooting is further improved. The variation in root mass of 16 varieties of Lolium perenne was studied under field conditions in two experiments on sandy soil in The Netherlands. The chosen varieties differed in genetic and aboveground characteristics such as ploidy, productivity and grass cover. Root dry matter (RDM) was measured in the 0-8, 8-16 and 16-24 cm soil layers. In summary, we found that RDM of perennial ryegrass differed significantly between varieties under field conditions. These differences were not linked to grass yield, which indicates that it is possible to select perennial ryegrass varieties that combine high aboveground productivity with high RDM. In the first experiment, which was managed by cutting, diploid varieties had higher RDM than tetraploid varieties. Grand mean RDM in the second experiment, which was managed by cutting as well as grazing, was lower than in the first experiment.In this experiment, total RDM was not influenced by ploidy but by grass cover type: high grass cover types had higher RDM. Differences in management between the two experiments possibly explain the differences in RDM and in the influence of chosen characteristics on RDM. Considering challenges in the areas of climate change, water availability, pollution and soil degradation, grass varieties with improved root systems could significantly contribute to a more efficient use of nutrients and water, erosion control, soil improvement and carbon sequestration.

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Samenvatting NL Het Waterschap Vallei en Veluwe, en LaMi hebben vergelijkend onderzoek gefinancierd van vijf sorghumgewassen en maïs op zandgrond te Woudenberg. De gemiddelde opbrengst van de vijf onderzochte sorghumgewassen was laag en gelijk aan die van maïs (11,5 ton ds/ha). Belangrijkste oorzaken zijn het droge en warme klimaat, en de minder goede bodemstructuur. Opgemerkt moet worden dat het maïsras drie tot vier weken later is gezaaid dan normaal. Wat betreft de voederwaarde hebben de meeste sorghumgewassen een relatief lager zetmeelgehalte, een lagere Vcos (Verteringscoëfficiënt van de Organische Stof), een relatief hoger ruweiwitgehalte en een relatief hoger ADL-gehalte (Acid Detergent Fiber). Geconcludeerd werd dat het sorghumras STH 16149 niet geschikt was als een hoogwaardig voedergewas. Het bodemvochtgehalte verschilde niet tussen rassen. Maïs had in de bodemlaag 0-90 cm de hoogste rest-N: 62 kg rest-N/ha, de gemiddelde waarde van de vijf sorghumrassen was 48 kg rest-N/ha. Per bodemlaag 0-30 cm, 30-60 cm en 60-90 cm waren er geen significante rasverschillen in rest-N (kg/ha) aangetoond. Summary EN The Waterboard Vallei en Veluwe, and LaMi have financed comparative research of five sorghum crops and maize on a sandy soil in Woudenberg. The average yield of the five sorghum crops studied was low and equal to those of maize (11.5 tonnes DM/ha). The most important causes are the dry and warm climate, and the poorer soil structure. It should be noted that the maize variety was sown three to four weeks later than normal. With regard to the feed value most sorghum crops have a relatively low starch content, low DCOM (Digestibility Coefficient of the Organic Matter), a relatively high crude protein content and a relatively high ADL (Acid Detergent Fiber) content, compared to maize. It was concluded that the sorghum crop STH 16149 was not suitable as a high-quality fodder crop. The soil moisture content did not differ between varieties. In the soil layer 0-90 cm, maize had the highest residual-N: 62 kg residual-N/ha, whereas the average value of the five sorghum varieties in this layer was 48 kg residual-N/ha. No significant differences between varieties were observed in residual-N (kg/ha) per soil layer 0-30 cm, 30-60 cm and 60-90 cm. Dit rapport is gratis te downloaden op https://doi.org/10.18174/469021 of op www.wur.nl/livestock-research (onder Wageningen Livestock Research publicaties).