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It has been proved that because of the different past of the parcels regarding their soil, agronomical and technological parameters, weed sampling results may not be generalised. Therefore it is necessary to study those solutions how to determine on an acceptable confidence level a parcel’s weed infestation with optimised sampling techniques.For studying the question we have delimited on wheat stubble a total sample area of 36×54 metres (using it as reference) and divided it into 2×2 cells giving a total of 486 sample cells. Then we surveyed the weed infestation and GPS recorded the location of each cell.We have analysed the weed infestation data with mathematical and statistical methods comparing the results of cells with each other and with the total sample area. We found that in several cases of different sample cells weed infestation displayed a diverse picture. This way sampling of weeds is extremely difficult.We found close relation between relative frequency of weeds and sampling accuracy. Therefore sampling is reliable only for surveying the frequent weeds in a parcel, while more rarely found weeds (e.g. spots of perennials) are to be scouted only by means of going over the parcel and GPS recording them. Otherwise, in the case of a traditional sampling process, the number of sampling cells required for acceptable reliability is unnecessarily high.Consequently, it is necessary to further study the economic and cost efficiency aspects of the needed weed sample density from the point of view of reasonable sample density, accuracy and optimal yield.

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In our 3-year study ground beetle assemblages were investigated in habitats with different weed coverage and insecticide treatments in an apple orchard in Hungary. The aim of the study was to compare the effects on the activity density and composition of carabid assemblages of two insecticide disturbance levels; 1) applications of selective insecticides (integrated plant protection, IPM - representing lower degree of disturbance); 2) applications of broad-spectrum insecticides (conventional plant protection - representing a higher degree of disturbance). Particular attention was paid to the joint effects of weed patterns in the orchard and insecticide treatments as well as to the carabid assemblages in the two neighbouring semi-natural habitats. The less intense insecticide disturbance significantly increased the activity density and species richness of the apple orchard carabid assemblages.  The mosaic habitats of the orchard herb layer, where higher and lower herb coverage alternate, altogether maintained more abundant and diverse carabid assemblages, than the habitat of closed, dense vegetation. The intra-orchard habitats with higher weed coverage enhanced the post-disturbance re-colonisation from the hedges, and therefore resulted carabid assemblages more similar to those of the semi-natural hedge vegetation. However, this re-colonisation was not great enough to compensate for the high mortality of the orchard carabid assemblage, which mostly consisted of species rare in the hedges. The high insecticide disturbance, affected the diversity of carabid assemblages in the intra-orchard habitats of high and low weed coverage differently, probably because of induced inter-habitat movement. Habitat attachment and post-disturbance recovery of Amara aenea, A. bifrons, A. fulva, A. ingenua, Broscus cephalotes, Calathus ambiguus, C. erratus, C. fuscipes, Cicindela hybrida, Harpalus albanicus, H. distinguendus, H. flavescens, H. froelichi, H. hirtipes, H. picipennis, H. rufipes, H. serripes, H. servus and H. tardus are also discussed.

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The cultivation methods used in the experiments resulted in marked differences in the weediness of maize and wheat. The least weediness was found in the conventional tillage treatment. The crucial question in the conservation and no tillage for sustainable agriculture is the weed problem, especially if the technology of weed controls is unaltered as compare to the traditional one. The lower yield in this cultivation system can be attributed to the competition of weeds. To clarify the question, investigations were carried out in the years 2005–2008 in a long-term field experiment set up on brown forest soil at the University of Pannonia, Georgikon Faculty Keszthely. The lowest yields were obtained in the wheat–maize no-tillage system in comparison to the others. This was valid at high and low levels alike (good and unfavorable years). On the average of years the yield decrease was 10–15% as compared to the traditional cultivation. In the spring survey of the weed cover (%) in the wheat trials it was found that the weed coverage increased parallel with the N fertilizer amounts, and then declined in the treatment above 200 kg N. The relation of weeds v.s. N fertilizer is similar to the second power equation of the yield curve. In case of the maize trials, there were no significant differences between the N treatments (25–30%) regarding weed coverage. The gained results call attention to the fact that with the propagation of the reduced soil cultivation systems it is necessary to modify and harmonize the practice of weed control and fertilization. Instead of the schematic weed control and fertilization process, the application of scientifically well-established methods should be urged. In sustainable agriculture the data collection of weeds, the survey of dominant species, special herbicide combinations and the means of precision agriculture have to be taken into consideration.

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Összefoglalás

Duna-Tisza közi karbonátos homoktalajon 1970-ben beállított NPK műtrágyázási kísérletünk 31–34. évében, 2000–2001 között vizsgáltuk a kezelések hatását a lucerna fejlődésére, gyomosodási viszonyaira, szénahozamára, valamint a talaj szántott rétegének ammóniumlaktát-ecetsav (AL) oldható PK-tartalmára. A termőhely talaja 1% körüli CaCO3-ot és humuszt, valamint 5–10% agyagot tartalmaz a szántott rétegben, az altalaj sok CaCO3-ot tartalmaz. A talajvíz 5–7 m mélyen található, a terület aszályérzékeny, oldható tápelemekkel (N, P, K) gyengén ellátott. A kísérletből levonható főbb következtetések:

  1. A 29 éve trágyázatlan talaj ammóniumlaktát-ecetsavas (AL) oldható PK-készlete kicsi. A talajgazdagító PK trágyázás nyomán az AL-PK készlet feltalajban 150–200 mg/kg AL-P2O5, ill. AL-K2O “kielégítő” tartományba emelkedett vagy meghaladta azt.
  2. Trágyázatlan kontroll talajon a lucerna 2001 tavaszán vontatottan kelt, fejletlen és alacsony maradt világoszöld színezettel. Az NP-kezelések közepes sarjadási erényt, magasságot és erősen zöld színt mutattak. A bőséges NPK trágyázás nyomán erőteljesen sarjadó, sűrű, fejlett, méregzöld állomány jött létre.
  3. Az évekkel, ill. az egymást követő kaszálásokkal a kontroll és az NP-parcellák állománya egyaránt fokozatosan kiritkult, elgyomosodott és fejlődésben visszamaradt. A negyedik évre, 2004 tavaszára a K-nélküli NP-kezelésekben a lucerna gyakorlatilag kipusztult, a gyomok nagyságrenddel nagyobb borítást mutattak. Az abszolút kontroll talajon a lucerna és a gyom borítása közel fele-fele arányt képviselt. A bőséges K-trágyázással (az N2P2K4 kezelésekben) a lucerna borítása nagyságrenddel haladta meg a gyomborítást és az összes növényfedettség 80% fölé emelkedett, a gyomfajok száma felére csökkent.
  4. A vizsgált évek (8 kaszálás) szénahozamait tekintve a kontroll talajon 6,8 t/ha, az N1P1 kezelésben 8,4 t/ha, az N2P2 kezelésben 9,5 t/ha, az N2P2K4 kezelésekben 12,5 t/ha termést kaptunk. Az NP-kezelések terméstöbbletei az első két évben jelentkeztek. A 3. és 4. évre a K-mal nem trágyázott talaj/altalaj felvehető K-készlete kimerült, és így részben alkalmatlanná vált a lucernatermesztésre.
  5. Az extrém K-hiányos talajon (NP kezelések) a madárhúr (CER AR) 18%-os, az árva rozsnok (BRO IN) 4–6%-os, a pásztortáska (CAP BU) 2%-os, az összes gyom 24–29%-os borítást ért el, míg a lucerna 2–4%-ot. A kísérletben 2000-ben 18 gyomfajt, 2004-ben 27 gyomfajt azonosítottunk. Az őszi árpa elővetemény után 2000 tavaszán uralkodó fajok a kétszikűek (Amaranthus spp.), voltak még 2004-ben az egyszikűek.
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