The profitability and environmental security of sustainable agriculture is, among other things, the result of balancing the management of mineral nutrients and organic matter at field and farm level; in the case of specialised farms also in the wider context of the sources of fodder, litter, substrate etc. used.
The crop nutrient balances take into account their income from all sources and their outflow with the crop harvested from the field. The nutrient balance is a method of optimising fertilisation. For farms located in Areas of Particular Concern (OSN), there is an obligation to carry out measures to reduce nitrogen run-off from agricultural applications. One element of the action programme is a nitrogen balance drawn up using the “over-field” method, as opposed to the “at farm gate” balance used to assess the situation on a farm-wide basis. The method for drawing up the balance is given in the regulation of the Minister of the Environment (Journal of Laws 2018, item 1339). A fertiliser balance should also be carried out for other nutrients, potassium and phosphorus, and a fertiliser plan should then be drawn up. In developing a fertiliser plan, it is helpful to keep documentation sheets for individual fields, where all agrotechnical treatments are recorded, as well as the yields and harvests obtained. Field record sheets should include, among other things, crop information, dates and amounts of organic and mineral fertilisation. Fertilisation documentation is also required in certified integrated production:
- fertilisation planning based on nutrient balances at field scale
- good agricultural practices in the fertilisation of agricultural land
The extent of the data required when documenting the application of fertilisers is set out in the relevant legislation on particularly vulnerable areas (OSN) and the principles of documentation in integrated plant production. The place where fertilisation was carried out (plot, field number), the type of crop, the rate and type of fertiliser applied, its name and composition are required. In the case of persons providing fertilisation services, it is required that they have completed the relevant training, which does not apply to graduates of agricultural colleges. In this case, the personal details of the person carrying out the fertilisation should be noted in the documentation. In other cases, the law does not require information on the person carrying out the fertilisation treatment, only on the owner of the field. However, it is also worth documenting this information, as it can be particularly useful on farms where different people carry out fertilisation, especially when it is necessary to reconstruct the fertilisation history and identify any irregularities. It also contributes to increasing the personal responsibility of employees for the fertilisation tasks they carry out. Fertilisation records form the basis for checks on the correctness of fertiliser application, for which the State Inspectorate for Environmental Protection (SIP) and, in the case of Integrated Production, the State Inspectorate for Plant and Seed Protection (PIORiN) are authorised.
The fertiliser balance should also take into account the relief and erosivity of the land. Fertilisation of soils on eroded land should vary across the different elements of the relief because of the significant habitat differences. Soils on slopes, which are easily washed out and therefore usually the poorest and quickly drying, require the most abundant fertilisation. Organic fertilisers are particularly suitable there. Weakly or not at all eroded soils on the topsoils require less fertilisation than on the slopes, and the deep and humus soils at the foot of the slopes and in the valleys generally require the least.