Filters
Impact of simulated acid rains on leakage of mineral elements from foliage of conifers and monocotyledons – adaptability matters
Deficiencies of Secondary Nutrients in Crop Plants-A Real Challenge to Improve Nitrogen Management
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.
Productivity of Nitrogen Accumulated in Alfalfa–Grass Sward Cultivated on Soil Depleted in Basic Nutrients: A Case Study
The productivity of fodder legumes, based on internal sources of N, may be limited due to an insufficient supply of nutrients responsible for the efficient use of N accumulated by the crop during the growing season. Production risk occurs on soils that are naturally poor or depleted in nutrients that are decisive for the fixation and utilization of N2 by alfalfa. This hypothesis was validated on the basis of a field experiment with an alfalfa–grass mixture carried out over three main seasons (2012−2014) on soil low in available potassium (K), calcium (Ca), and sulfur (S). The experiment involved two factors that contained two levels of applied gypsum (GYP: 0, 500 kg ha−1) fertilized with P and K (POT: absolute control—AC, P60K0, P60K30, P60K60, and P60K120). In each main season of the alfalfa–grass mixture, the sward was mowed three times (three cuts). The total sward yield (TY) reached its maximum in the second main season (15.6 t DW ha−1), then it significantly decreased. The sward yield of the third cut was the main driver of the TY. The content of P in the first cut, and especially P and S in the third cut of the sward, affected the N:P and P:S ratios, which, in turn, determined the productivity of the alfalfa–grass mixture. The total amount of accumulated N (TN) in the sward significantly responded to gypsum and PK fertilizers. In the first and third main seasons, the highest TN was found on the plot fertilized with both gypsum and 120 kg K2O ha−1. In the second main season, the TY was determined by PK dose, being variable in successive years. The highest total N accumulation (TN) was recorded in the second main season. It reached 504 kg N ha−1 on the plots with GYP−0 and 436 kg N ha−1 for GYP−500. However, the corresponding TY was 16.7 and 17.3 t DW ha−1. This apparent discrepancy was due to the much higher productivity of N, which was 33.2 and 39.6 kg fodder DW ha−1 TN, respectively. These two characteristics clearly indicate that the productivity of the accumulated N by the alfalfa–grass sward was significantly restricted by the shortage of P and S. The studies clearly emphasized that the sward of the alfalfa–grass mixture grown on soil depleted in available K, Ca, and S responds significantly to the combined application of gypsum and potassium, but provides effective control of the P supply, even on soil rich in available P.
Sulfur added to cattle slurry as a means to improve the nitrogen economy of maize during the grain filling period
Nitrogen Hotspots on the Farm—A Practice-Oriented Approach
The proactive management of nitrogen (N) on a farm is the best way to protect the environment against N pollution. The farm is the basic business unit, where simple and low-cost methods of identifying and ameliorating weaknesses (nitrogen hotspots) in the N-flow chain can be applied. The basis for the effective use of mineral N fertilizers (Nf) is the farmer’s knowledge of the farm’s own N resources, their quantity, and the potential availability for growing crops. These resources include both primary sources of N (N2 fixed by legumes) and those that are recyclable, which include crop byproducts and manure. On the other hand, crop requirements must be accurately quantified to exploit the yield potential of the crop varieties grown on the farm. The basic challenge for the farmer is to maximize the use efficiency of the N resources. In this regard, the farmer has two diagnostic tools available to recognize nitrogen hotspots and to quantify N resources. These are (1) the N balance method (difference between the N inputs and outputs), which allows for a surplus or deficiencies in the N-flow between farm units (fields, livestock housing) to be identified, and (2) the nitrogen gap, which is based on the amount of Nf applied and the yield of a given crop. It is possible to calculate the maximum attainable yield as well as identify the fields on the farm that require a correction of N management.
Does Elemental Sulfur Act as an Effective Measure to Control the Seasonal Growth Dynamics of Potato Tubers (Solanum tuberosum L.)?
The in-season dynamics of potato tuber biomass (TTB) growth requires effective nitrogen (N) control. This hypothesis was tested in 2006 and 2007. The two-factorial experiment with two rates of N (60, 120 kg ha−1) and sulfur (S; 0, 50 kg ha−1) was carried out in the split-plot design. The third factor was the sampling of plants at 10-day intervals. The collected plant material was divided into leaves, stems, stolons + roots, and tubers. The seasonal trend of TTB was linear, while the biomass of leaves, stems, and stolons + roots was consistent with polynomial regression models. TTB was controlled by (i) the date of potato growth after emergence, when the TTB exceeded the leaf biomass (DAEcrit); (ii) the stem growth rate; and iii) the share of stems in the total potato biomass. TTB growth was reduced when DAEcrit preceded the DAEop for leaf biomass, determining its maximum. This phenomenon appeared in 2007 on plots fertilized only with N. The absolute growth rate of the stem biomass, exceeding ¼ of that of the tuber biomass in the descending phase, resulted in an increased and prolonged share of stems in the total potato biomass, which ultimately led to a decrease in tuber yield. The use of sulfur to balance the N, applied effectively, controlled the growth rate of potato organs competing with tubers.
Efektywność ekonomiczna i energochłonność produkcji pszenżyta jarego w zależności od systemu uprawy roli i nawożenia siarką
Balanced Fertilization of Winter Wheat with Potassium and Magnesium—An Effective Way to Manage Fertilizer Nitrogen Sustainably
In agricultural practice, in addition to determining the nitrogen (Nf) dose, it is necessary to effectively control its effect on currently grown crops. Meeting these conditions requires not only the use of phosphorus (P) and potassium (K), but also nutrients such as magnesium (Mg) and sulfur (S). This hypothesis was verified in a single-factor field experiment with winter wheat (WW) carried out in the 2015/2016, 2016/2017, and 2017/2018 growing seasons. The experiment consisted of seven variants: absolute control (AC), NP, NPK-MOP (K as Muriate of Potash), NPK-MOP+Ki (Kieserite), NPK-KK (K as Korn–Kali), NPK-KK+Ki, and NPK-KK+Ki+ES (Epsom Salt). The use of K as MOP increased grain yield (GY) by 6.3% compared to NP. In the NPK-KK variant, GY was 13% (+0.84 t ha−1) higher compared to NP. Moreover, GYs in this fertilization variant (FV) were stable over the years (coefficient of variation, CV = 9.4%). In NPK-KK+Ki+ES, the yield increase was the highest and mounted to 17.2% compared to NP, but the variability over the years was also the highest (CV ≈ 20%). The amount of N in grain N (GN) increased progressively from 4% for NPK-MOP to 15% for NPK-KK and 25% for NPK-KK+Ki+ES in comparison to NP. The nitrogen harvest index was highly stable, achieving 72.6 ± 3.1%. All analyzed NUE indices showed a significant response to FVs. The PFP-Nf (partial factor productivity of Nf) indices increased on NPK-MOP by 5.8%, NPK-KK by 12.9%, and NPK-KK+Ki+ES by 17.9% compared to NP. The corresponding Nf recovery of Nf in wheat grain was 47.2%, 55.9%, and 64.4%, but its total recovery by wheat (grain + straw) was 67%, 74.5%, and 87.2%, respectively. In terms of the theoretical and practical value of the tested indexes, two indices, namely, NUP (nitrogen unit productivity) and NUA (nitrogen unit accumulation), proved to be the most useful. From the farmer’s production strategy, FV with K applied in the form of Korn–Kali proved to be the most stable option due to high and stable yield, regardless of weather conditions. The increase in the number of nutritional factors optimizing the action of nitrogen in winter wheat caused the phenomenon known as the “scissors effect”. This phenomenon manifested itself in a progressive increase in nitrogen unit productivity (NUP) combined with a regressive trend in unit nitrogen accumulation (NUA) in the grain versus the balance of soil available Mg (Mgb). The studies clearly showed that obtaining grain that met the milling requirements was recorded only for NUA above 22 kg N t−1 grain. This was possible only with the most intensive Mg treatment (NPK-KK+Ki and NPK-KK+Ki+ES). The study clearly showed that three of the six FVs fully met the three basic conditions for sustainable crop production: (i) stabilization and even an increase in grain yield; (ii) a decrease in the mass of inorganic N in the soil at harvest, potentially susceptible to leaching; and (iii) stabilization of the soil fertility of P, K, and Mg.
Soil Fertility Clock—Crop Rotation as a Paradigm in Nitrogen Fertilizer Productivity Control
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 (Nf). 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 Nf 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 Nf 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.