Study on Tillage Systems and Residue Management Application on Yield and Yield Components of Wheat (Triticum aestivum L.) in Mashhad Condition

The continuation of agricultural operations, based on conventional ploughing along with removal or burning of plant residues, can lead to soil degradation and erosion. Taking into account the increase in environmental pollution, the exploitation of new technologies in the direction of sustainable agriculture should be taken seriously. Along with conservation tillage, maintaining or adding plant residues, especially wheat mulch, on the soil surface can also be emphasized. Increased yield, stimulated soil microbial activity, improved soil structure and reduced water erosion are among the beneficial consequences of wheat residues on the soil.Determining the effects of crop residue and tillage systems on productivity is essential for sustainable land management. Therefore, the current experiment was carried out with the aim of investigating the effect of different tillage systems and wheat residue levels on growth indicators, yield and yield components of wheat.

In order to study the effect of tillage systems and residue management on yield and yield components of wheat, a field study was conducted as a split block experiment in a randomized complete block design with three replications. Experiment was implemented at experimental site of Ferdowsi University of Mashhad, Iran in 2013 growing season to evaluate the impact of tillage systems and wheat residue application on growth parameters, yield and yield components of wheat. For this purpose, four different tillage systems (disk, mouldboard plough + disk, sweep plough + disk and chisel plough + disk) as were employed vertical factor in combination with five different crop residue applications (0, 25, 50, 75 and 100% wheat residue) as horizontal factor. Number of ear per plant, seed number per ear and plant, 1000 seed weight, grain and biological yields of wheat were determined. Experimental data were analysed considering the analysis of variance using SAS 9.3. In order to determine the statistical differences between treatments, the least significant difference (LSD) was performed at level of P ≤ 0.05.

According to the results, the highest leaf area index and crop growth rate of wheat were observed in 167 and 151 days after sowing. These times were equal to beginning of seed filling. Chisel plough + disk tillage system increased leaf area index and crop growth rate by 14 and 21%, respectively compared with mouldboard plough + disk tillage system. In addition, the lowest and the highest ear number per plant and seed yield were observed when disk and chisel plough + disk tillage systems were applied, respectively. In general, the chisel system creates relatively deep furrows in the soil, but unlike the mouldboard plough, it does not cause overturning. As a result, at the same time as a decrease in the loss of moisture and nutrients, slight changes in the soil structure are caused.The results showed that by increasing wheat residues up to 75%, the leaf area index and plant growth rate considerably increased. For example, at the level of 75%, these traits were registered up to 35 and 60%, respectively, more than the control treatment. Moreover, ear number per plant and seed yield was significantly increased with increasing crop residue application. In a general statement, providing as much organic matter and nutrients as possible is considered one of the main benefits of applying wheat residues on the soil surface. Hence, an increase in the leaf area index, growth rate, and seed yield of wheat following the application of straw residues may be due to the gradual decay of plant residues during the growing season and subsequently the availability of nutrients required for plant growth. 

Application of wheat residue along with reduced tillage (based on disk and chisel plough) as an ecological approach can be recommended in arid and semi-arid regions of Iran to increase wheat yield and promote sustainable production.