| Sažetak | Poznato je da neke prakse obrade tla negativno djeluju na sadržaj organske tvari, strukturu tla i zbijenost. Konzervacijski sustavi obrade tla predstavljaju pozitivnu alternativu za očuvanje strukture, konzervaciju tla i vode. Nastoji se pronaći optimalna agrotehnička praksa kojom će se ublažiti negativni utjecaj klimatskih promjena na poljoprivrednu proizvodnju i degradaciju tla. Cilj istraživanja je u agroekološkom području testirati utjecaj sustava obrade tla na određena svojstva fluvisola (volumnu gustoću tla, mehanički otpor tla, trenutačnu vlažnost tla, kapacitet tla za vodu, stabilnost strukturnih agregata, sadržaj organske tvari) i prinos kultura u trogodišnjem razdoblju. Pokusno polje postavljeno je na Pokušalištu Šašinovec (Sveučilišta u Zagrebu Agronomski fakultet) u split-plot raspored s trima ponavljanjima za svaki sustav obrade (CT - oranje lemešnim plugom (18 – 20 cm) u jesen (A) + tanjuranje u proljeće; MT - obrada tla kombiniranim oruđem (kultivator+tanjurača+valjak) (10 – 15 cm) u proljeće; RT - podrivanje (35 – 40 cm) u jesen (A) i primjena kombiniranog oruđa (10 – 15 cm) u proljeće) u razdoblju od 2019. do 2021. godine. Svaki blok (100 m x 10 m) predstavlja različit sustav obrade te je razdvojen na dio s malčem (slamom) ili bez malča koji čini podfaktor (50 m x 10 m) pokusa. Uzorkovanje je provedeno na Pokušalištu Šašinovec u proljeće poslije sjetve i u jesen poslije žetve svake istraživane godine. Ukupno je kroz trogodišnji period uzeto 648 uzoraka tla koji su analizirani u ovlaštenom laboratoriju te 216 terenskih mjerenja uzorkovano penetrometrom. Prema dobivenim rezultatima, korištenje malča i reducirane obrade (MT i RT) smanjuje volumnu gustoću tla, pri čemu je pod RT varirao ovisno o vremenu uzorkovanja dok je pod MT nakon primjene u drugoj godini istraživanja pozitivan efekt zabilježio kontinurano do kraja istraživanja. Utvrđeni su mehanički otpori ispod ograničavajućih vrijednosti za razvoj korijena prilikom svih mjerenja te je kontinuirana primjena vertikalne obrade s malčem ključna za smanjenje zbijenosti tla. Plitka obrada (MT) malčem povećala je kapacitet zadržavanja vode u tlu i trenutačnu vlažnost tla tijekom višegodišnjeg istraživanja. Prethodno navedena obrada nakon tri godine ostvarila je povećanje stabilnosti strukturnih agregata. Sadržaj organske tvari se povećavao najviše nakon tri godine primjene MT-a. Prinosi su varirali tijekom tri godine istraživanja. Soja nije pokazala značajne razlike dok je kukuruz imao najbolje rezultate s dubokom podrivanjem tla u drugoj godini. Treća godina je pokazala da je jara pšenica s primjenom slame imala značajno veće prinose. Kombinacija analize fizikalnih svojstava tla s praćenjem prinosa ratarskih kultura omogućuje bolje razumijevanje utjecaja obrade tla i primjene malča na održavanje plodnosti tla i poljoprivrednu proizvodnju. Zabilježeni su pozitivni utjecaji plitke obrade sa zadržavanjem malča, nasuprot konvencionalnom okretanju tla gdje niti zadržavanje malča ne pridnosi smanjenju degradacije fizikalnih svojstva. Ujednačeni prinosi na testiranim sustavima ukazuju na prednosti napuštanja tradicionalnih sustava obrade tla i lakši prelazak na konzervacijske sustave. U budućnosti je potrebno nastaviti istraživanje u drugim agroekološkim uvjetima te ukazivati na nedostatke i degradaciju tla konvencionalnim sustavom obrade tla. |
| Sažetak (engleski) | The management of Fluvisols represents a crucial aspect of sustainable agriculture due to
their high fertility and susceptibility to soil degradation. Among the numerous factors
influencing soil health and crop productivity, impact of tillage practices and straw management
stands out as a critical area of study. This integrated approach plays a pivotal role in shaping
the physical properties of Fluvisols and significantly affects crop yield. Tillage practices,
ranging from conventional to conservation methods, profoundly influence Fluvisol structure
and soil-water dynamics. The choice of tillage method determines the degree of soil
disturbance, affecting soil aggregation, porosity, and moisture retention. Additionally, it
influences the breakdown of organic matter and nutrient availability, ultimately impacting the
soil's fertility and capacity to support crop growth. Understanding the intricacies of different
tillage techniques and their repercussions on Fluvisol physical properties is essential for
sustainable land management. Simultaneously, the management of straw, a crop residue, is
gaining recognition for its role in soil health. Incorporating straw into Fluvisols alters soil
structure, enhances organic matter content, and influences moisture retention. Strategic straw
management practices, such as mulching or incorporation into the soil, present opportunities
to mitigate erosion, reduce evaporation, and bolster soil fertility. However, the effectiveness of
these strategies is contingent upon various factors including climate, soil type, and crop
rotation. This study aims to delve into the integrated impact of tillage practices and straw
management on the physical properties of Fluvisols and subsequent crop yield. By scrutinizing
the interactions between these practices, it endeavors to provide insights that can guide
sustainable soil management strategies tailored to Fluvisol characteristics and regional
agricultural needs. Through a holistic understanding of these interactions, this research seeks
to contribute to the development of informed agricultural practices that optimize productivity
while preserving the long-term health and fertility of Fluvisol.
The research was conducted on the surfaces of the Šašinovec Experimental Farm, University
of Zagreb Faculty of Agriculture (45°50' N; 16°11' E; 120 m above sea level), in the area of the
City of Zagreb. The location belongs to the Western Pannonian region. The average annual
temperature is 10,4 °C, while the average annual precipitation is 852,3 mm. The soil texture is
silt clay loam (Fluvisol). The soil is slightly alkaline, with moderate humus content, rich in P2O5
and K2O, and well supplied with total nitrogen content. The experimental field was set up in a
split-plot design with three replications for each tillage system. Each block (100 m x 10 m)
represents a different tillage system, with mulch (straw) or without mulch as a sub-factor (50
m x 10 m). The tillage systems are as follows: conventional tillage - plowing with a moldboard
plow (18 - 20 cm) in autumn and harrowing in spring; minimum tillage - soil tillage with
combined implements (cultivator + harrow + roller) (10 - 15 cm) in spring; reduced tillage -
subsoiling (35 - 40 cm) in autumn and application of combined tool (10 - 15 cm) in spring.
Shredded wheat straw is applied every year after sowing the designated crop at a rate of 2,75
t/ha (140 kg per plot). Planned crops (soybean, maize, wheat) were sown according to the
usual crop rotation. Sampling and soil property analysis for the following soil physical
properties were monitored: soil water content, bulk density, water holding capacity, penetration
resistance, water-stability of structural aggregates. Soil samples for soil analysis were taken
immediately after sowing and immediately after harvesting. Samples were taken from two
depths (0 - 10 cm; 10 - 20 cm) in three replications for each depth, totaling 108 samples per
measurement. Soil water content, bulk density, and water holding capacity were determined
by gravimetric drying at 105 °C over a period of 72 hours from an undisturbed soil sample with
a volume of 100 cm3. The dynamics of compaction status will be monitored by handheld
penetrometer (Eijkelkamp Penetrologger). The measurement procedure included 4
replications per plot, totaling 72 measurements per sampling. Samples for determining the
water-stable aggregates percentage were air-dried after careful preparation by hand, and then
vibrationally sieved for 30 seconds. Each fraction of aggregates was weighed to determine
their proportion in the soil using Kemper and Rosenau (1986) method. For climate
interpretation of the 30-year period meteorological data from the Zagreb-Maksimir station was
used and compared with dana from meteorological station at the Šašinovec Experimental
Farm. Yields were determined by weighing each harvested plot. The organic matter content
will be determined on each plot (a total of 18 samples per measurement). Statistical data
analysis, (two-factorial) experiment will be set up in a split-plot design, with tillage as the main
factor and mulching as the sub-factor. The impact of tillage, mulch, and their interactions on
yield and soil physical properties was tested for each year of the study. Data on soil physical
properties throughout the years of the study was statistically analyzed using analysis of
variance (ANOVA) adapted for split-plot design, utilizing the statistical program SAS 14.3.
According to the results, the combination of mulch and RT reduced the bulk density of the soil
in the first year of the trial, while the MT and CT treatments had no positive effect. Penetration
resistance measurements were below the root development thresholds throughout the
experiment and there were no positive effects of the reduction in penetration resistance by the
interaction of mulch and RT on the tested treatments in the first year. MT and RT with mulch
increased the water holding capacity of the soil in contrast to the bare treatments, and the
same positive effect was found for soil water content in the previously mentioned treatments.
The values of water-stable aggregates were not affected in the CT and MT treatments with
mulch, while a relative increase in stability was observed in the RT treatment with mulch
compared to the treatments without and with mulch. The organic matter content was not
positively influenced by the MT and RT treatments with mulch, while the CT treatment with
mulch had a positive effect in contrast to the treatment with mulch. The yield of soybeans
reached relatively higher values in MT and RT treatments with mulch than in untreated
treatments. In the following experimental year, the bulk density was significantly lower only in
the RT treatment with mulch than in the MT and CT treatments with mulch. A similar effect was
observed when measuring the penetration resistance. The water holding capacity of the soil
was significantly higher in the MT and RT treatment with straw than in the CT treatment with
straw. There were also significant differences in soil water content values, with MT and RT
treatments with mulch having higher values than CT treatments with mulch, furthermore, all
mulch treatments had higher values than the treatments without mulch. Interestingly, the
values for the water-stable aggregates were higher in the bare MT and RT treatments than in
the mulch treatment. The same effect was observed in the values for organic matter content
and yield of maize. In the third year of the trial, the bulk density was lower in the MT and RT
treatment with mulch than in the CT treatment with mulch. Significantly lower penetration
resistance was observed in all treatments with mulch compared to bare stems. In terms of
water holding capacity, MT and RT treatments with mulch had significantly higher values than
bare plots. For soil water content, MT and RT tree with mulch showed significantly higher
values than CT tree with mulch. The value of water-stable aggregates was significantly higher
in the MT treatment with mulch than in the other mulch treatments. The organic matter content
was also significantly higher in the MT treatment with mulch than in the other mulch treatments.
Finally, the yield of spring wheat was significantly higher in the MT and RT treatments with
mulch than in the CT treatment with mulch. In summary, it can be said that the continuous
application of non-inverting tillage with mulch contributes significantly to the reduction of soil
degradation. From the collected results, it can be concluded that the use of conventional
ploughing is no longer necessary, as soil degradation is greater and yields are not higher than
with other vertical tillage systems. The continuous use of straw mulch also contributes
significantly to improving the physical properties of the soil and maintaining the sustainability
of land use. Furthermore, tillage systems that combine vertical and shallow tillage with mulch
can mitigate the losses caused by ever-changing climatic conditions while providing farmers
with economic and environmental stability. |
