Influence of tillage methods and soil crust breakers on cotton seedling emergence in silty-loam soil

Abstract

Soil crusting is a common problem that affects crop emergence and growth worldwide across different soil and climate conditions. This study aimed to investigate the impact of various tillage methods on soil crust formation and assess the effectiveness of soil crust breakers in enhancing cotton seedling emergence. The research was conducted on Silty-Loam soil, examining the impact of four tillage methods: Method A, a conventional tillage approach employing a moldboard plow, disc harrow, and roller; Method B, a conservation tillage method involving a chisel plow, disc harrow and roller; Method C, another conventional tillage method utilizing a chisel plow, powered rotary tiller, and roller; and Method D, another conservation tillage approach utilizing a disc harrow and roller. Two types of crust breakers, a rolling type, and a skid blade type, were tested. The results showed significant variations in soil crusting hardness among the tillage methods, with conservation tillage methods B and D being the most effective in reducing penetration resistance. The post-crust-breaking penetration resistance declined, decreasing from 305 to 408 kPa in the control plots to 60–93 kPa in the treated plots. Breaking the soil crust with the crust breakers considerably reduced penetration resistance, improving soil conditions for seedling emergence and root growth. Seedling emergence was significantly influenced by tillage methods, with conservation tillage methods B and D promoting the highest emergence rates. The mean percent emergence of subplots (with crust breaker applications) was 77.8% when the chisel plow, disc harrow, and roller were applied (Method B) and 78.2% when the disc harrow and roller were applied for tillage (Method D). The percentage of emerged cotton seedlings in the control plots ranged from 51.1% to 86.2%, with the tillage method order of C < A < B < D. However, the soil crust-breaking treatments were effective in increasing the percentage of emerged cotton seedlings for all tillage methods. The rolling-type crust breaker was particularly effective in breaking the crust and enhancing emergence for methods A and C. It increased the emergence percentage by 27.1% for method A and 34% for method C. The study also revealed that the hardness of the soil crust significantly affected emergence time and emergence rate index. Harder soil crusts resulted in longer mean emergence times and lower emergence rate indices. The conventional tillage method involved a chisel plow, powered rotary tiller, and roller, contributing to a harder soil crust with the highest penetration resistance recorded at 408 kPa for the control plot (without soil crust breaking). This resulted in the longest emergence time of 9.8 days and the lowest emergence rate index of 0.38 seedlings/m·day. However, after the soil crust-breaking treatment, the differences in emergence time and emergence rate indices among different tillage methods and crust breakers became statistically insignificant (P>0.05).