Zielewicz Waldemar, Grzebisz Witold, Biber Maria
Department of Grassland and Natural Landscape Sciences, Poznan University of Life Sciences, Wojska Polskiego 28, 60-637 Poznan, Poland.
Agricultural Chemistry and Environmental Biogeochemistry, Poznan University of Life Sciences, Wojska Polskiego 28, 60-637 Poznan, Poland.
Plants (Basel). 2023 Jun 8;12(12):2250. doi: 10.3390/plants12122250.
It was assumed that the production of alfalfa in soils naturally poor in available nutrients, such as potassium (K) and calcium (Ca), depends on the use of fertilizers. This hypothesis was validated in an experiment with an alfalfa-grass mixture carried out in 2012, 2013 and 2014 on soil formed from loamy sand that had a low content of available Ca and K. The two-factor experiment consisted of two levels of applied gypsum as a source of Ca (0, 500 kg ha) and five levels of PK fertilizers (absolute control, P60K0, P60K30, P60K60 and P60K120). The total yield of the sward was determined by the main seasons of alfalfa-grass sward use. Gypsum application increased the yield by 1.0 t ha. The highest yield of 14.9 t ha was obtained on the plot fertilized with P60K120. Based on the nutrient content in the sward, it was shown that the main yield predictor was the content of K in the first cut of sward use. The reliable yield predictors, based on the total accumulation of nutrients in the sward, turned out to be K, Mg and Fe. The nutritional quality of the alfalfa-grass fodder, based on the K/Ca + Mg ratio, depended mainly on the season of the sward use, which was substantially deteriorated by the K fertilizer. Gypsum did not control this process. The productivity of the nutrients taken up by the sward depended on the accumulated K. Its yield-forming effect was significantly limited by manganese deficiency. The use of gypsum positively affected the uptake of micronutrients, consequently increasing their unit productivity, especially of manganese. Optimization of the production of alfalfa-grass mixtures in soils poor in basic nutrients requires micronutrients to be taken into account. Their uptake by plants can be limited by high doses of basic fertilizers.
据推测，在天然有效养分（如钾（K）和钙（Ca））匮乏的土壤中种植苜蓿，依赖于肥料的使用。这一假设在2012年、2013年和2014年于由砂壤土形成且有效钙和钾含量低的土壤上进行的苜蓿 - 禾本科牧草混播实验中得到了验证。该两因素实验包括两种作为钙源的石膏施用量水平（0、500公斤/公顷）和五种磷钾肥施用量水平（绝对对照、P60K0、P60K30、P60K60和P60K120）。草地产量由苜蓿 - 禾本科牧草地的主要利用季节决定。施用石膏使产量提高了1.0吨/公顷。在施用P60K120的地块上获得了最高产量14.9吨/公顷。根据草地产量中的养分含量表明，主要的产量预测指标是首次刈割时草地中钾的含量。基于草地中养分的总积累量，可靠的产量预测指标是钾、镁和铁。基于钾/钙 + 镁比例的苜蓿 - 禾本科牧草饲料的营养品质主要取决于草地利用季节，钾肥会使其显著变差。石膏无法控制这一过程。草地吸收养分的生产力取决于积累的钾。其增产效应受到锰缺乏的显著限制。施用石膏对微量养分的吸收有积极影响，从而提高了它们的单位生产力，尤其是锰。在基本养分匮乏的土壤中优化苜蓿 - 禾本科牧草混播的生产需要考虑微量养分。高剂量的基肥可能会限制植物对它们的吸收。
