Secondary nutrient (e.g., calcium, magnesium, sulfur) deficiencies in crop plants disturb the nitrogen balance in the plants, thus reducing the overall yield. This hypothesis was analyzed based on the physiological functions of these nutrients, in relation to the uptake and utilization of N, in crop plants. Nitrogen uptake by plants requires a well-developed root system, the size of which depends on the supply of calcium. This process is largely controlled by the content of toxic aluminum in the soil, which can be mitigated through the application of lime and/or gypsum. In humid climates, the excessive uptake of calcium by plants occurs during water shortages; this process significantly interferes with N uptake. Magnesium, which affects plant growth throughout the growing season, can effectively control excessive calcium uptake. Magnesium deficiency can be ameliorated with soil- or foliar-applied fertilizers. These stages define the timing of plant sampling and determination of the N:S ratio, as an indicator of plant nutritional status. The application of Mg, S, or MgS facilitates higher productivity of fertilizer N by narrowing the N:Mg and N:S ratios in plants. The use of secondary nutrients can allow farmers to obtain high yields while reducing both production costs and environmental risks.

The Soil Fertility Clock (SFC) concept is based on the assumption that the critical content (range) of essential nutrients in the soil is adapted to the requirements of the most sensitive plant in the cropping sequence (CS). This provides a key way to effectively control the productivity of fertilizer nitrogen (N_f). The production goals of a farm are set for the maximum crop yield, which is defined by the environmental conditions of the production process. This target can be achieved, provided that the efficiency of N_f approaches 1.0. Nitrogen (in fact, nitrate) is the determining yield-forming factor, but only when it is balanced with the supply of other nutrients (nitrogen-supporting nutrients; N-SNs). The condition for achieving this level of N_f efficiency is the effectiveness of other production factors, including N-SNs, which should be set at ≤1.0. A key source of N-SNs for a plant is the soil zone occupied by the roots. N-SNs should be applied in order to restore their content in the topsoil to the level required by the most sensitive crop in a given CS. Other plants in the CS provide the timeframe for active controlling the distance of the N-SNs from their critical range.

The agricultural usability of biogas digestate solids (BDS) as a soil amendment depends upon its impact on soil fertility and the content of minerals in the edible part of the grown crop. This hypothesis was verified in a series of field experiments with maize conducted between 2014 and 2016 at Brody, Poland. The two-factorial experiment consisted of the DBS application method (broadcast and row) and its rate: 0, 0.8, 1.6, 3.2 t ha^–1. The post-harvest analysis of soil fertility showed that BDS can, at least partly, replace mineral fertilizers. The supply of N-NO₃ to maize as a growth driving factor was significantly limited by a shortage of iron, potassium and, to some extent, magnesium. As recorded in 2016, the shortage of available Fe resulted in a low/pool of N-NO₃, thus significantly decreasing the yield of grain. The shortage of K supply to grain created a pathway for the accumulation of other elements, including heavy metals. The disadvantage of the N-NO₃ pool increase, due to the DBS application, was concomitant with the enhanced intake of cadmium and lead, which consequently exceeded their permissible concentration limits in grain. These unfavorable results of biogas digestate impact on the quality of maize grain can be ameliorated by incorporating zinc into the biogas type of soil amendment and keeping a sufficiently high level of available potassium and iron. The shortage of K can be partly overcome by a better sodium supply, however, its accumulation in grain results in an enhanced accumulation of cadmium and lead.

The in-season trend of onion biomass and its yield depend on the dynamics of nitrogen (N) and sulfur (S) uptake. This hypothesis was verified based on a three-year (2009, 2010, 2011) field study (Poznan University of Life Sciences). The experimental factors consisted of N: 0, 60, 120 and S: 0, 30, 60 kg ha⁻¹. The dynamics of onion total dry weight (TDW), total N uptake (TNU), and total S uptake (TSU) were determined at 10-day intervals. The in-season course of TDW and TNU was best described by the expolinear and TSU by the quadratic growth model. Sulfur uptake increased in onion at day after emergence (DAE) 40, independent of its rate with respect to SN control, resulting in increased N by 50%, and consequently higher yield. The maximum absolute S uptake rate (SC_m), a factor defining yield, increased progressively with the N rate, but only in the absence of S application. Plants fertilized simultaneously with S and N showed a more complicated impact on SC_m. The N rate of 120 kg ha⁻¹ resulted in SC_m reduction, leading to a yield drop. The expolinear model indicated an onion growth disturbance, revealed under unfavorable growth conditions, leading to yield depression.

The key objective of winter oilseed rape cultivation, resulting from its broad spectrum of uses, is to harvest maximum yield of oil. It has been formulated a hy...

It has been assumed that phosphorus (P) resources accumulated in vegetative tissues of winter oilseed rape (WOSR) at flowering are too low to cover the requirements for the high-yielding crop during the seed filling period (SFP). The data used originated from field experiments with nutrients sequentially added to WOSR, using crops grown on soil rich in available P (2008–2010). The low-seed density canopies during SFP resulted only from the P remobilized from the pre-flowering crop resources. The high-seed density canopies depended on both P remobilized and its uptake from soil (PFPU). The maximum PFPU of 30.7 kg P ha⁻¹, and the concomitant seed density of 86.8 ∙ 10³ m⁻², resulted in a maximum seed yield of 5.8 t ha⁻¹. Internal P resources were reused during SFP irrespective of the initial P content and without impact on phosphorus use efficiency (PUE). The study showed that PUE improvement in WOSR is related to the seed density of primary branches. Its development depended on the supply of potassium, magnesium and sulfate. A PUE of 105.4 kg seed kg⁻¹ P was used to predict the seed yield gap (PYG). This index can be used as a measure of P management efficiency in WOSR canopy.