Laura Masilionytė

Experimental analysis of CO2 emissions from agricultural soils subjected to five different tillage systems in Lithuania

Intensive agricultural production strongly influences the global processes that determine climate change. Thus, tillage can play a very important role in climate change. The intensity of soil carbon dioxide (CO₂) emissions, which contribute to the greenhouse effect, can vary depending on the following factors: the tillage system used, meteorological conditions (which vary in different regions of the world), soil properties, plant residue characteristics and other factors. The main purpose of this research was to analyse and assess the effects of autumn tillage systems with different intensities on CO₂ emissions from soils during different seasons and under the climatic conditions of Central Lithuania. The research was conducted at the Experimental Station of Aleksandras Stulginskis University from 2009 to 2012; and in 2014. The soils at the experimental site were classified as Eutric Endogleyic Planosol (Drainic). The investigations were conducted using five tillage systems with different intensities, typical of the Baltic Region. Deep conventional ploughing was performed at a depth of 230-250 mm, shallow ploughing was conducted at a depth of 120-150 mm, deep loosening was conducted at depths of 250-270 mm, and shallow loosening was conducted at depths of 120-150 mm. The fifth system was a no-tillage system. Overall, autumn tillage resulted in greater CO₂ emissions from the soil over both short- and long-term periods under the climatic conditions of Central Lithuania, regardless of the tillage system applied. The highest soil CO₂ emissions were observed for the conventional deep ploughing tillage system, and the lowest emissions were observed for the no-tillage system. The meteorological conditions greatly influenced the CO₂ emissions from the soil during the spring. Soil CO₂ emissions were enhanced as precipitation and the air and soil temperatures increased. Long-term investigations regarding the dynamics of CO₂ emissions from soils during the maize vegetation period indicated that autumn tillage systems affect the total soil CO₂ emissions. The highest (2.17 μmol m(-2)s(-1)) soil CO₂ emissions during the vegetation period were observed in the deep ploughing tillage system, and the lowest values were observed (1.59 μmol m(-2)s(-1)) in the no-tillage system.

The effect of alternative cropping systems on the changes of the main nutritional elements in the soil@@@Pagrindinių mitybos elementų pokyčiai dirvožemyje taikant alternatyvias žemdirbystės sistemas

Experiments were conducted at Joniskėlis Experimental Station of the Lithuanian Research Centre for Agriculture and Forestry in 2006–2013, on an Endocalcari-Endohypogleyic Cambisol (CMg-n-w-can), which is characterised by low phosphorus and high potassium contents with low ( 2.1) humus content. The research was carried out in the crop rotation’s grass-cereal sequence: perennial grasses (grown as green manure) → winter wheat. The aim of experiments is to determine the changes of biogenic soil elements in the organic cropping systems by using farmyard manure and aftermath of red clover for green manure or their combinations for winter wheat fertilization, and in sustainable cropping systems – by replenishing the amount of nutritional elements with mineral fertilizers. The NPK balance was negative in the organic cropping system in the soil with both low and moderate levels of soil humus when only green manure had been used as fertilizer for winter wheat. The NP balance was strongly positive and K was significantly in excess in the organic cropping system when the green manure had been used in combination with 40 Mg ha-1 of farmyard manure. A marked reduction in the available phosphorus content in the soil with different humus levels was established when green manure or 40 Mg ha-1 of farmyard manure or their combinations had been applied. Also, potassium levels increased in the organic cropping system where green or farmyard manure had been applied. When 40 Mg ha-1 of farmyard manure and N30 mineral fertilizer had been used in the sustainable cropping system to promote straw mineralization, the nitrogen balance in the soil with the low humus content was slightly positive, but in the soil with moderate humus content it was strongly negative; in the soil of both humus levels phosphorus balance was slightly positive and potassium balance was significantly excessive. In the both soils with low and moderate humus content, in the sustainable cropping systems that had used the perennial grass aftermath as green manure with minimum rates of mineral fertilizer N30P60K60, N balance was negative, P – marginally positive. In the soil with low humus content K value was positive, in the soil with moderate humus content – marginally negative. In the sustainable cropping system, where perennial grass aftermath for green manure and N30P60K60 had been used for winter wheat during two 4-field crop rotations the available phosphorus and potassium quantity in the soil low and moderate in humus status showed a trend towards decreasing.