Witold Szczepaniak

EFFECT OF BALANCED NITROGEN FERTILIZATION IN FOUR- YEAR ROTATION ON PLANT PRODUCTIVITY

Increased nitrogen use efficiency, NUE, in crop plant production is the main challenge for agriculture in this century. Any success in this objective achievement requires to take into account not only phosphorus and potassium but also secondary nutrients, such as magnesium and sulfur, at least. In order to check this hypothesis a series of annual field experiments were conducted in 2005, 2006, 2007 and 2006, testing in the four course rotation response of following crops: maize  spring barley  winter oil-seed rape  winter wheat to increasing level of nitrogen nutritional balance imposed by set of treatments comprised potassium and magnesium. The obtained results clearly indicated on maize as the most productive crop, irrespective of the imposed fertilizing system. The highest yields of the tested crops were harvested on plots fertilized with NPK and Kieserite, provide that potassium was applied as Korn-Kali. Effects of the imposed systems of fertilizer N balancing have been assessed by means of two NUE indices, such as: (i) partial factor productivity of fertilizer nitrogen (PFPN) and agronomic net efficiency of fertilizer nitrogen (AEN). Both indices were useful in making a reliable evaluation of tested treatments, but the AEN was more conspicuous as a NUE index. The most pronounced effect of the applied nutrients on yield development was through improvement of kernel/grain number per plant. This fact indirectly stresses on the importance of the period extending from the stage of ear growth to the stage of kernel/grain growth as decisive for final grain yield establishment. The net balance of plant available potassium and phosphorus showed that their net surplus with respect to yield response was negative, in turn indicating on magnesium as a nutrient required to reach nutritional balance of N, P, K in high-yielding crops.

Evaluation of fertilizers solubility and phosphate release in slightly acidic arable soil

ABSTRACT The geochemical reactivity of single superphosphate (SSP), triple superphosphate (TSP), phosphate rock (PR), partially acidulated phosphate rock (PAPR) and potassium dihydrogen phosphate (KH2PO4) was evaluated in an incubation trial. The soil was Anthrosols, Ap horizon (Sandy loam). Solubility equilibrium of phosphates was calculated by phosphate (PPot = logH2PO4 – pH) and calcium (CaPot = logCa + 2pH) potentials. Next, activity ratio (AR°) and Woodruff potential (ΔF) were considered for estimating phosphate dynamics in the soil. Data showed that phosphate potentials stressed on significant solubility process and varied accordingly to the rates of the fertilizers: −5.50, −4.81, −4.47 and −4.09 for 0, 50, 100 and 150 kg P ha−1. The values of the Woodruff potential (ΔF) varied widely from −1929 to 8573 cal mol−1, i.e., from marginal supplying power in the case of the control treatment to very high supplying power for the TSP (Triple superphosphate). These findings are of practical value for the following reasons: TSP and KH2PO4 are recommended for quick and high P supply to plants; SSP and PAPR for moderate supply and finally PR for slow and low supply. Phosphorus efficiency should be treated with priority particularly for areas with intensive cropping and susceptibility to runoffs.

Phosphorus sources for winter oilseed rape (Brassica napus L.) during reproductive growth – magnesium sulfate management impact on P use efficiency

ABSTRACT 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.

Mineral composition of winter oilseed rape (Brassica napus L.) seeds as a tool for oil yield prognosis

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 hypothesis, which assumed that mineral composition of seeds allows a reliable prediction of both crude oil concentration (COC), and yield of oil (YOI). This concept has been validated in three 2007/08, 2008/09, 2009/10 seasons. The field experimental design was composed of six fertilizing treatments: absolute control (AC), NP, NPK, NPKMgS1 (1/3 total MgS rate applied in spring), NPKMgS2, (total MgS rate applied in autumn), NPKMgS3 (2/3 - autumn, 1/3 - spring). The COC depended on both factors, but any interactional effect was found. The YOI was a result of interaction of both factors, reaching the highest value of 2.6 t*ha-1 in 2008 in the plot fertilized with NPKMgS2. The COC was a result of positive impact of calcium and negative by both nitrogen, and magnesium. The YOI was the best predicted by calcium concentration. It has been found that any calcium concentration increase above 3.0 g*kg-1 DM resulted in decrease of the crude oil yield. The prediction of both oil characteristics was more reliable based on nutrient accumulation in seeds. As again magnesium was the key predictor of COC, exerting a negative impact on this characteristic. The optimum set of YOI predictors was depended on the group of treatments. In all considered treatments, the YOI was affected by the interactional effect of phosphorus (negative), and potassium (positive). In the set of treatments, composed of NPK and its variants with MgS rates, the YOI was depended on the amount nitrogen and zinc in seeds. The first nutrient affected positively and the second negatively the yield of crude oil.

Sustainable Management of Soil Potassium – A Crop Rotation Oriented Concept

Modern agriculture is under pressure of two contradictory challenges reflected by the increas‐ ing world’s population on one hand, and the magnitude of food production, on the other hand. In the period ranging from 1960 to 2010, the population doubled from 3 to more than 6 billions, while the production of cereals tripled, a success which expressed by a significant yield in‐ crease per ha (from 1.09 t ha-1 in 1960 to 3.0 t ha-1 in 2010) [1]. The major reason of such yield in‐ crease was a marked progress in plant breeding, resulting in generations of new, high-yielding varieties [2]. This process run in parallel with the increase in fertilizers, pesticides production and consumption, hence enabling to cover nutritional needs and supporting the health of highyielding crops. The intensive production gain, based on enormous consumption of non-renew‐ able resources, especially fuel and simultaneously nutrients such as nitrogen and phosphorus was, however, concomitant with their low use efficiency. This type of agriculture intensifica‐ tion created, in many regions of the world a threat to environment, at both local and globalscale. There are numerous examples stressing the negative impact of intensive agriculture on environment. Agricultural practices are responsible for the majority of ammonia and to a great part for nitrogen oxides emission to the atmosphere. Pollution of ground-water by nitrates and phosphates originating from both arable soils and surface waters was recognized the earliest. All these negative effects were the reason for the increased activity of local societies in the 70 and 80-ies of the XX century, resulting in the development of legal instruments protecting the environment, for instance the Nitrate Directive [3, 4, 5].