{"id":15711,"date":"2026-11-04T15:58:33","date_gmt":"2026-11-04T15:58:33","guid":{"rendered":"https:\/\/edapro.ch\/?p=15711"},"modified":"2026-11-04T16:17:15","modified_gmt":"2026-11-04T16:17:15","slug":"protein-bread-wheat-nitrogen","status":"publish","type":"post","link":"https:\/\/edapro.ch\/en\/protein-bread-wheat-nitrogen\/","title":{"rendered":"Protein in bread wheat: why nitrogen alone is not enough"},"content":{"rendered":"

More nitrogen does not automatically mean more protein. In the leaf, the nitrogen has to become amino acids, and for that the plant needs partners: magnesium, boron, sulphur, molybdenum. If one is missing, the nitrogen stays unused. Here is where that happened in our own wheat.<\/p>\n

Two stages from light to protein<\/h2>\n

The plant builds protein in two stages. First photosynthesis: it delivers sugar and with it the energy. For this it needs magnesium, iron, manganese, nitrogen and phosphorus. What the plant does not use itself, it sends into the soil as root exudates and so feeds the microbiology.<\/p>\n

Then protein synthesis: sugar and nitrogen become amino acids, and the amino acids become protein. This is where boron, sulphur and molybdenum come in.<\/p>\n

The mechanism is clearest for molybdenum. It is a cofactor of nitrate reductase, the enzyme that converts nitrate into ammonium, the first step towards an amino acid. Sulphur is part of the amino acids cysteine and methionine. Boron is involved in nitrogen metabolism and sugar transport.<\/p>\n

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\ud83c\udf3e<\/div>\n
Two stages, seven nutrients<\/strong>Stage 1, photosynthesis:<\/strong> magnesium, iron, manganese, nitrogen, phosphorus  \u00b7  Stage 2, protein:<\/strong> boron, sulphur, molybdenum<\/div>\n<\/div>\n

What our leaf showed on 7 April<\/h2>\n

On 7 April 2025 we sampled young leaves of our winter wheat in Ruswil. I explain how the leaf is built up in the post on leaf sap analysis<\/a>. Here we look at the values of the protein chain.<\/p>\n

Sugar was at 5.3 %, with an optimum of 0.5 to 2.8 %. Nitrate was low at 44 ppm (optimum below 150), and total nitrogen was in range at 2796 ppm. So photosynthesis was running, and the nitrogen was being processed.<\/p>\n

\"Leaf
Winter wheat, young leaf, our own plot in Ruswil, sample of 7 April 2025.<\/figcaption><\/figure>\n

Below the optimum were three partners of the protein chain: magnesium at 128 ppm (optimum 250 to 430), sulphur at 164 ppm (360 to 590) and boron at 0.37 ppm (0.40 to 1.20). Molybdenum, at 0.07 ppm, was within the optimum but at the lower end (0.05 to 0.20).<\/p>\n

In my opinion this is exactly the situation in which a crop looks good and still has room to improve on protein. We did not measure what this means in the grain. The leaf shows where the bottleneck probably lies, not the protein value at harvest.<\/p>\n

What you can do in spring<\/h2>\n

Make up the missing nutrients through the leaf. This is faster than through the soil, which is often cold or dry in spring. Our guideline values for cereals:<\/p>\n