This article demonstrates the influence of the method using application of 100 kg N/ha of nitrogen fertilizer and hybrid types of maize (Zea mays L.) on selected efficiency indicators used for this macroelement. It was shown that in comparison to traditional broadcast fertilization, fertilization in rows or fertilization in rows combined partly with top dressing increased the values of such characteristics as nitrogen uptake and use, percentage of fertilizer nitrogen in the total nitrogen uptake as well as the agricultural and physiological effectiveness of the nitrogen. All the studied nitrogen effectiveness factors for maize (apart from physiological effectiveness) were significantly higher for the stay-green cultivar. In relation to a traditional cv. ES Palazzo, the cv. ES Paroli stay-green was characterised by poorer use of the nitrogen uptake regardless of the nitrogen fertilizer application method, which was visible in the lower values of physiological effectiveness.

A strict field experiment with maize was carried out in the years 2009–2011 at the Experimental Station of the Poznań University of Life Sciences. The impact of mineral fertilization levels on the nutritional status of plants at an early development stage 5–6 leaves (BBCH 15/16) was assessed, as well as the possibility of using biomass and the current state of nutrient supply to predict grain yield. The adopted assumptions were verified on the basis of field experiments with nine variants of mineral fertilization and two maize varieties (EURALIS Semences, Lescar, France) (ES Palazzo and ES Paroli SG—“stay-green” (SG)). Regardless of the variety tested, the plants were under-nutritioned with calcium and magnesium. Plant nutritional status and the accumulation of minerals at the BBCH 15/16 stage were the main factors determining the variability of maize grain yields. In addition, it was shown that maize biomass in the BBCH 15/16 stage, calcium content and the N:K ratio significantly determined grain yield of traditional variety. The yield of the “stay-green” hybrid was largely shaped by plant biomass in the BBCH 15/16 stage, potassium, calcium, magnesium contents and N:Mg ratio. Regression analysis showed that grain yield of the tested maize varieties was determined by plant biomass and its content from 59% to 69%.

This study presents the results of 3-year field trials, whose purpose was to assess the dynamics of dry matter accumulation by maize depending on the placement depth of a two-component (NP) mineral fertilizer in the soil layer, type of nitrogen fertilizer and date of its application. Weather conditions, mainly thermal in the early growing season, had a significant effect on maize responses to placement depth of phosphorus starting dose in the soil profile. In the initial stage of maize development, the temperature determined plant growth to a significantly higher extent than the sum of rainfall. The dry matter yield of ears and whole plants showed a clear reaction to starter phosphorus fertilization, but the effect of the depth of fertilizer placement varied over the years, indicating a depth of 5 cm and 10 cm as advisable and recommended for agricultural practice. The PFPFN (partial factor productivity of fertilizer nitrogen) and PFPFP (partial factor productivity of fertilizer phosphorus) indices confirmed the significant effect of fertilizer (NP) placement in the soil profile, indicating row fertilizer application (regardless of the depth) as recommended to improve the efficiency of maize fertilization. The SPAD (soil plant analysis development) leaf greenness index turned out to be a sensitive indicator of maize response to fertilizer (NP) placement depth in the soil profile.

Field experiments showed the occurrence of such agrophages as the frit fly (Oscinella frit L.) and the European maize borer (Pyrausta nubilalis Hbn.). Identified diseases included fusariosis (Fusarium ssp.) and maize smut (Ustilago maydis Corda). The incidence of the frit fly was influenced by weather conditions, mainly temperature, in the period from sowing to the BBCH 15–16 phase. Moderate temperature conditions contributed to the occurrence of the pest. The significantly highest percentage of plants damaged by larvae of this pest was recorded on maize fertilised only with potassium (K) and phosphorus with potassium (PK). In turn, the lowest percentage of plants damaged by frit fly larvae was recorded for maize fertilised with nitrogen and potassium (NK). The percentage of plants damaged by the European maize borer was influenced by temperature and humidity conditions in individual years of the study. The highest percentage of plants damaged by larvae of the pest was found in the vegetation season characterised by the highest amount of rainfall with the lowest mean daily air temperature. The presence of potassium in a given fertiliser combination, the application of manure or combined application of manure and mineral fertilisation resulted in an enhanced resistance of maize plants to Fusarium ssp. fungi. The significantly greatest infestation of maize plants by the fungus Ustilago maydis Corda was recorded in the treatment in which only nitrogen was applied. In turn, the lowest percentage of plants with symptoms of this disease was recorded in the treatment with the application of potassium alone and in the application of potassium together with phosphorus.

In the period 2017–2019, field experiments were conducted at the Research and Education Center Gorzyń, unit Złotniki (52°486′ N; 16°819′ E), Poznan University of Life Sciences, at the Luvisols, under natural weather conditions, to evaluate the effect of multifunctional methylated seed oil (EXP 1, 2, and 3) and standard adjuvants (AtB and S) on the efficacy of mixtures phenmedipham + ethofumesate and metamitron applied in full (PEM 1) and reduced rates (PEM 2) in sugar beet. Field studies were carried out and three applications of herbicides were administrated subsequent to the emergence of weeds (BBCH 11–12). PEM applied at reduced rates with EXP was more effective than after AtB and S adjuvants. They enabled the attainment of high and consistent efficacy of herbicides (with EXP—96–97%, AtB—97%, S—95%, compared to PEM 1—93%, and PEM 2—82%), irrespective of varying weather conditions during, and subsequent to, their application. The sugar beet root yield from herbicide treatments after tested adjuvants was higher than from the untreated control and after application of reduced rates of herbicides without adjuvants.