Chandra A. Madramootoo

Bio: Chandra A. Madramootoo is an academic researcher from McGill University. The author has contributed to research in topics: Irrigation & Drainage. The author has an hindex of 36, co-authored 203 publications receiving 4467 citations.

Soil microbial dynamics in maize-growing soil under different tillage and residue management systems

Abstract: The long-term impact of tillage and residue management on soil microorganisms was studied over the growing season in a sandy loam to loamy sand soil of southwestern Quebec, growing maize ( Zea mays L.) monoculture. Tillage and residue treatments were first imposed on plots in fall 1991. Treatments consisted of no till, reduced tillage, and conventional tillage with crop residues either removed from (−R) or retained on (+R) experimental plots, laid out in a randomized complete block design. Soil microbial biomass carbon (SMB-C), soil microbial biomass nitrogen (SMB-N) and phospholipid fatty acid (PLFA) contents were measured four times, at two depths (0–10 and 10–20 cm), over the 2001 growing season. Sample times were: May 7 (preplanting), June 25, July 16, and September 29 (prior to corn harvest). The effect of time was of a greater magnitude than those attributed to tillage or residue treatments. While SMB-C showed little seasonal change (160 μg C g −1 soil), SMB-N was responsive to post-emergence mineral nitrogen fertilization, and PLFA analysis showed an increase in fungi and total PLFA throughout the season. PLFA profiles showed better distinction between sampling time and depth, than between treatments. The effect of residue was more pronounced than that of tillage, with increased SMB-C and SMB-N (61 and 96%) in +R plots compared to −R plots. This study illustrated that measuring soil quality based on soil microbial components must take into account seasonal changes in soil physical and chemical conditions.

Soil bulk density and crop yield under eleven consecutive years of corn with different tillage and residue practices in a sandy loam soil in central Canada

Abstract: Different tillage and residue practices could potentially lead to significant differences in both crop production and soil properties, especially if both practices are implemented over a long time period and on continuous monoculture corn (Zea mays L.). The objective of this research was to determine how differing tillage practices and corn residues affected soil bulk density, corn emergence rates and crop yields over an 11-year period. The experimental site consisted of three tillage practices (no-till, NT; reduced tillage, RT; and conventional tillage, CT) and two residue practices (with grain corn residue, R; without residue (corn crop harvested for silage), NR). Bulk density was 10% higher in NT (1.37 Mg m−3) than in CT (1.23 Mg m−3), particularly at the 0–0.10 m depth. Spring corn emergence in NTR was slower by 14–63% than all other treatments in 1992–1994. In 1996, corn emergence in the NTR treatment was 18–30% slower, and NTNR was 5–30% faster than all other treatments. No-till with residue (NTR) possibly had the slowest overall emergence due to the higher surface residue cover (8.5 Mg ha−1 in 1996) and higher bulk density (1.37 Mg m−3 over the 11 years). Long-term mean dry matter corn yields were not affected by tillage and residue practices during the course of this study; rather climatic-related differences seemed to have a greater influence on the variation in dry matter yields. The long-term cropping of corn under different tillage and residue practices can change bulk density in the surface soil layer, vary the corn emergence without affecting yields, and produce comparable yields between all the tillage and residue practices.

Effects of water stress at different growth stages on greenhouse tomato yield and quality

Abstract: Tomatoes (Lycopersicon esculentum Mill. cv. Sunstart) were grown in a greenhouse during Summer 1999 and again in Winter 2000. Two available soil water (ASW) deficit thresholds, 65% and 80%, at which plants were irrigated to field capacity were factorially combined with five irrigation timing patterns: 1) no water stress; 2) stress throughout the entire growing season; 3) stress during first cluster flowering and fruit set 4) stress dur- ing first cluster fruit growth; and 5) stress during first cluster fruit ripening. Crop yields, water use efficiency, as well as maximum and minimum equatorial fruit diameters and fruit height were measured. Quality parameters of soluble solids, pH, and fruit color were also measured. Water stress throughout the growing season significantly reduced yield and fruit size, but plants stressed only during flowering showed fewer but bigger fruit than completely non-stressed plants. Consequently, on a weight basis the stressed at flowering and nonstressed plants had similar yields. Nonstressed and flowering-stressed fruit showed lower soluble solids and a lighter color of red ripe fruit than the other stress treatments. No significant differences in yield or quality were found between the two stress levels (65% vs. 80% ASW depletion before irrigation). Water stress only during flowering resulted in better yields and quality than stress at other specific developmental stages or at all times, but equal or poorer yields and water use efficiency than nonstressed plants. quality of greenhouse tomatoes was studied during Summer 1999 and again in Winter 2000. In both years, identical experiments were set up in the Macdonald Campus greenhouse of McGill Univ. in Montreal, Quebec. Two available soil water (ASW) deficit levels, 65% and 80%, at which irrigation up to field capacity was implemented were factorially combined with five irrigation timing patterns: (1) no stress (NS); (2-4) stress during flow- ering and fruit set (F), fruit growth (G), or fruit ripening (R) of the first cluster; and (5) stress from flowering through ripening of the first cluster (FGR), in a randomized complete- block design with four replicates. This resulted in nine treatments, as the "NS" controls for both 65% and 80% ASW were identical and hence reduced to a single treatment. Plants were grown in 24-cm-high polyethyl- ene pots that had an upper diameter of 28 cm and a diameter of 22 cm at the base, and a mean inner diameter of 24.5 cm in the por- tion containing soil (soil volume of roughly 9.6 L/pot). Each pot was placed in a 55 × 28.5 × 7-cm white plastic seedling tray on the concrete floor of the greenhouse, in order to trap any irrigation overflow or soil mate- rial escaping from the drainage holes at the base of the pots. Plants were spaced 60 cm apart both within and between rows. Natural lighting was supplemented with overhead lighting to provide a daylength of 16 h. The overhead lighting consisted of 400-W (fixtures rated for 485W, 208V, 2.5 A) high-pressure sodium bulbs (P.L. Light Systems, Canada), resulting in a photosynthetic photon flux (PPF) at canopy level of s 60 µmol·m -2 ·s -1 . The daytime temperature was maintained at 25 ± 2 °C, and the nighttime temperature at 18 ± 2 °C. Relative humidity (RH) was main- tained at 65% ± 5% throughout the growing season.

Climate Change 2007: The Physical Science Basis.

Abstract: Cause, conseguenze e strategie di mitigazione Proponiamo il primo di una serie di articoli in cui affronteremo l’attuale problema dei mutamenti climatici. Presentiamo il documento redatto, votato e pubblicato dall’Ipcc - Comitato intergovernativo sui cambiamenti climatici - che illustra la sintesi delle ricerche svolte su questo tema rilevante.

The role of conservation agriculture in sustainable agriculture.

Abstract: The paper focuses on conservation agriculture (CA), defined as minimal soil disturbance (no-till, NT) and permanent soil cover (mulch) combined with rotations, as a more sustainable cultivation system for the future. Cultivation and tillage play an important role in agriculture. The benefits of tillage in agriculture are explored before introducing conservation tillage (CT), a practice that was borne out of the American dust bowl of the 1930s. The paper then describes the benefits of CA, a suggested improvement on CT, where NT, mulch and rotations significantly improve soil properties and other biotic factors. The paper concludes that CA is a more sustainable and environmentally friendly management system for cultivating crops. Case studies from the rice-wheat areas of the Indo-Gangetic Plains of South Asia and the irrigated maize-wheat systems of Northwest Mexico are used to describe how CA practices have been used in these two environments to raise production sustainably and profitably. Benefits in terms of greenhouse gas emissions and their effect on global warming are also discussed. The paper concludes that agriculture in the next decade will have to sustainably produce more food from less land through more efficient use of natural resources and with minimal impact on the environment in order to meet growing population demands. Promoting and adopting CA management systems can help meet this goal.