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A significant drop of 2.4-2.9 percentage-points (%-p) in crude protein content (on dry matter basis) in Danish grain crops was observed from around 1990 to 2015. The aim of the analysis was to quantify the effect of the change in N-response of varieties of winter wheat (WW) and spring barley (SB) under farmers’ conditions based on approx. 1000 fertilizer trials with WW and 500 with SB carried out in farmers’ fields from 1987 to 2015. Results indicated that for WW receiving 129-190 kg N/ha, DM yield increased 0.8-0.9 Mg/ha. The amount of harvested N in grain increased 5-11 kg N/ha, and % N in grain dropped by 0.1-0.05 %-points; the largest drop was found for low N-additions. For SB, receiving 93-129 kg N/ha, DM yield increased by 0.9-1.1 Mg/ha. The amount of harvested N in grain increased by 4-6 kg while the N % in grain dropped 0.2-0.24 %-points. For both crops, the effect of plant breeding is likely to be confounded with the effect of increased CO2. Adding up effects of changed N-response and fertilizer rates only explained part of the observed reduction in crude protein content.

Soil organic carbon (SOC) is broadly recognised as an important parameter affecting soil quality, and can therefore contribute to improving a number of soil properties that influence crop yield. Previous research generally indicates that soil organic carbon has positive effects on crop yields, but in many studies it is difficult to separate the effect of nutrients from the effect of SOC in itself. The aim of this study was to analyze whether the SOC content, in itself, has a significant effect on potential yields of commonly grown cereals across a wider range of soil types in Denmark. The study draws on historical data sets from the Danish national field trials consisting of 560 winter wheat (Triticum aestivum L.) trials and 309 spring barley (Hordeum vulgare L.) trials conducted over the past 20 and 17 years, respectively. We hypothesised that for these two crops, the potential grain yield, the yield with no fertiliser N application and the N use efficiency would be positively affected by SOC level. A statistical model was developed to explore relationships between SOC and potential yield, yields at zero N application and N use efficiency (NUE). The model included a variety of variables and aimed to elucidate the sole effect of SOC by controlling for potential confounding variables. No significant effect of SOC on potential winter wheat was found, whilst for spring barley, only for the course sandy loam soil type was a borderline significantly positive effect of SOC on potential yields found. The relationship between unfertilized plot yields and SOC was positive for winter wheat, although not significant, whilst for spring barley a significant positive effect of SOC was found only for the coarse sandy soil type, and a borderline significant positive effect of SOC was found for the coarse sandy loam soil type. A significant negative relationship was found between SOC and NUE for both winter wheat and spring barley. Based on the large dataset analyzed, we cautiously

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Planteanalyser kan give et øjebliksbillede af, hvilke nærignsstoffer planten mangler

One-hundred-ten samples of onion (Allium cepa Hysam) from 11 Danish sites (10 onions from each site) uncontaminated by human activities other than normal agricultural practices were collected and analyzed for 63 major and trace elements using a newly developed high-resolution inductively coupled plasma mass spectrometry method. Sample handling, sample preparation, and analysis of the samples were performed under carefully controlled contamination-free conditions. Mean concentrations of the elements (micrograms per kilogram of fresh weight) were compared with those reported previously from other surveys. The results provide useful biological and nutritional information on onions.

The multielement (Ag, Al, Au, B, Ba, Be, Bi, Ca, Cd, Ce, Co, Cr, Cu, Dy, Er, Eu, Fe, Ga, Gd, Ge, Hf, Ho, Ir, La, Lu, Mn, Mo, Nb, Nd, P, Pb, Pd, Pr, Pt, Re, Rh, Sb, Sc, Se, Si, Sm, Sr, Ta, Tb, Te, Th, Ti, Tl, Tm, U, V, Y, Yb, Zn, and Zr) levels in peas (Pisum sativum Ping Pong) are presented in this paper. The peas were collected from 10 background areas, on Funen and mid-Jutland, Denmark, with intensive cultivation with use of fertilizer and pesticides. High-resolution inductively coupled plasma mass spectrometry (HR-ICPMS) was used for the analyses of the samples. The contents of the elements are generally at the same levels or even lower than those reported from other surveys. The results provide useful biological, nutritional, and background level information on peas.