In field trials in 1993-94 on sandy soils at 2 sites in the Netherlands, cattle slurry was applied by injection into slots 25 cm apart (standard injection) or 75 cm apart (banded injection). Subsequently, maize cv. Melody or Mandigo was sown at a row spacing of 75 cm parallel to the slots, either at random lateral positions in the standard injection treatment or 10 cm from the injection slots of the banded injection treatment. All treatments, including a control without slurry, were combined with 0 or 20-31 kg/ha of subsurface banded P starter fertilizer. Dry matter yields of silage maize were on average reduced by 8% when standard injection of slurry was not supplemented with P. However, the yield reduction was only 2% when slurry was banded.

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In field experiments in 1982-89 at 2 sites in the Netherlands, potatoes cv. Bintje and sugarbeet cv. Monohil or Ovatio in a wheat/potatoes/wheat/sugarbeet rotation were preceded during winter by fallow or a green manure crop of Lolium multiflorum cv. Tetila with 0 (G0), 100 (G100) or 200 kg N/ha (G200) or Trifolium pratense cv. Rotra with no N (RC). Green manure crops were undersown to winter wheat cv. Durin and ploughed in in the first half of November. On average, G0, G100, G200 and RC had then accumulated 22, 93, 125 and 57 kg N/ha, respectively, in the above-ground plant parts. G0 crops tended to immobilize soil mineral N in spring and generally had non-significant effects on the yields of potatoes and sugarbeet, whereas G100, G200 and RC increased the N yields and marketable yields significantly. Effects were mainly attributable to the release of N by the green manures. The fertilizer value of the green manures was evaluated by their effect on economic optimum N rates, the marketable yield and the N yield when no mineral fertilizer N was supplied. The last two methods appeared to be most appropriate for the present experiments. Fertilizer values ranged from -21 to 108 kg N/ha, depending on the type of green manure crop and the calculation method. About half of the N accumulated in above-ground parts of the green manure crop was available to potatoes and sugarbeet from G100 when evaluated by its effect on N yields. From G200 this was even greater, although this may partly have resulted from the transfer of fertilizer N that had not been taken up by the green manure crop. Due to a high content of N in roots and stubble, RC provided, on average, almost double the amount of N accumulated in the above-ground plant parts. Green manure crops also had a minor positive effect on grain yields of winter wheat following potatoes and sugarbeet. At least 35% of the above-ground N in L. multiflorum green manure crops was not utilized within the first 18 months after their incorporation.

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