Puddling coarse-textured soils for rice culture in the irrigated tract of the Indo-Gangetic Plains causes high soil strength in the upper layers. This may adversely affect growth and yield of following upland crops. It is possible that no-tillage (NT) in wheat (without residues of preceding rice crop) could aggravate this problem and reduce fertilizer nitrogen (N) use efficiency. In certain production scenarios, NT has been reported to be advantageous because it allows for earlier planting of wheat by eliminating delays caused by tillage. This study examined the combined effects of two crop establishment options for wheat in relation to fertilizer N and planting time following puddled rice cultivation in an irrigated environment of Punjab, northwest India. Combinations of two establishment systems, NT-direct planting and conventional-tillage (CT) with soil disruption to 0.10 m depth in main plots, with two N rates, 120 and 150 kg ha−1 in subplots, were evaluated. Variation in planting time, 31 October (D1) and 7 and 10 November (D2), was used to evaluate effect of planting-earliness. Under D1 in NT, grain yield of wheat was comparable to that under D2 in CT. However, under no advancement of wheat planting in NT, grain yield was 0.2–0.3 t ha−1 less than that in CT. This yield reduction in NT could be overcome by adding 30 kg ha−1 more fertilizer N suggesting that tillage enhanced N use efficiency. These tillage gains are ascribed to the greater extraction of profile stored and applied water and nutrients because of denser crop rooting caused by reduction in soil strength and less weed competition. Higher N use efficiency in CT suggests that farmers could achieve fertilizer N savings with this system. Comparing the tillage systems showed that NT was more cost-effective than CT even after accounting for the cost of additional fertilizer N (saving of Rs. 1685 ha−1) to overcome associated yield penalties under no advancement in planting time.

Agricultural research and development (R&D) would benefit from reliable yet cheap technology uptake indicators to guide decision making. The paper explores the use of village surveys to monitor technology use and illustrates this through two empirical case studies into tillage dynamics in the Trans-Gangetic Plains in northwest India. The first case study is a revisit of 50 communities surveyed earlier in Haryana State. The second case study is a new and wider representative sample of 120 villages across Haryana and Punjab States. The case studies illustrate that after an initial rapid spread of tractor-drawn zero tillage drills for wheat seeding in these intensive systems, the zero + reduced tillage area seems to have stabilized there at between a fifth and a quarter of the wheat area. Conventional tillage for wheat continues to decline, with an increased use of rotavators making up the difference – but its intensive shallow tillage goes against the conservation agriculture tenets. The paper illustrates the potential of village surveys to provide timely and cost-effective feedback to agricultural R&D.

Impact assessment hinges on reliable indicators of technology uptake, but this poses particular challenges for new agronomic practices in emerging economies. This paper presents a triangulation approach to assess technology diffusion and illustrates it by assessing the extent and dynamics of zero tillage wheat in South Asia's rice-wheat systems. Various diffusion indicators from three different data methods (secondary data, supply-side surveys, demand-side surveys) are contrasted for two different locations (India's Haryana State and Pakistan's Punjab province) for the period 2000–2004. Such multi-indicator, multi-site and multi-year triangulation enhances the robustness of the inferences and provides the necessary perspective. The three sources coincide in terms of diffusion of zero tillage wheat having increased since 2000, but in particular the empirical surveys show a much slower uptake and subsequent stagnation in the Pakistan Punjab study area. The paper thereby reiterates the need for empirical ground truthing of technology uptake and the need for robust and complementary diffusion indicators.

Conservation agriculture (CA) systems are based on minimal soil disturbance, crop residue retention and crop rotation. Although the capacity of rotations to break pest and disease cycles is generally recognized, other benefits of crop rotations in CA systems are seldom acknowledged and little understood. We monitored different conventional and CA cropping systems over the period from 2005 to 2009 in a multi-seasonal trial in Monze, southern Zambia. Both monocropped maize and different maize rotations including cotton and the green manure cover crop sunnhemp (Crotalaria juncea) were compared under CA conditions, with the aim of elucidating the effects of crop rotations on soil quality, soil moisture relations and maize productivity. Infiltration, a sensitive indicator of soil quality, was significantly lower on conventionally ploughed plots in all cropping seasons compared to CA plots. Higher water infiltration rate led to greater soil moisture content in CA maize treatments seeded after cotton. Earthworm populations, total carbon and aggregate stability were also significantly higher on CA plots. Improvements in soil quality resulted in higher rainfall use efficiency and higher maize grain yield on CA plots especially those in a two- or three-year rotation. In the 2007/08 and 2008/2009 season, highest yields were obtained from direct-seeded maize after sunnhemp, which yielded 74% and 136% more than maize in the conventionally ploughed control treatment with a continuous maize crop. Even in a two-year rotation (maize-cotton), without a legume green manure cover crop, 47% and 38% higher maize yields were recorded compared to maize in the conventionally ploughed control in the two years, respectively. This suggests that there are positive effects from crop rotations even in the absence of disease and pest problems. The overall profitability of each system will, however, depend on markets and prices, which will guide the farmer's decision on which, if any, rotation to choose.

With a focus on eastern Africa, the results of research on the ecophysiology and water relations of tea are reviewed. In particular, work undertaken at the Ngwazi Tea Research Station (formerly Unit) in southern Tanzania is synthesized and interpreted in relation to work reported from elsewhere in Africa (and beyond where appropriate). Topics covered include factors influencing: the components of yield, yield distribution, root growth, stomatal behaviour, photosynthesis, transpiration, xylem water potential and how cultivars vary in their responses to water stress. A companion paper (Carr, 2010) reviews the results of research on the irrigation of tea, water productivity, and its practical significance to the tea industry and the wider scientific community.

With a focus on eastern Africa, the results of research on the water requirements and responses of tea to irrigation and drought are reviewed. In particular, work undertaken at the Ngwazi Tea Research Station (formerly Unit) in southern Tanzania is synthesized. Topics covered include: crop water use, yield responses to water for mature and immature tea, comparisons between clones (including composite plants), plant density/water availability interactions, dry matter production and partitioning, drought mitigation, crop modelling and irrigation systems. Emphasis is placed on the practical aspects of the work and its relevance to the tea industry it serves. A companion paper reviews our understanding of the water relations of the tea plant and, in particular, the mechanisms responsible for the responses observed in the field.

Hardening of Coffea arabica saplings by watering cycles (WCs) might be a suitable practice to achieve higher tolerance to low leaf water potential (Ψleaf) before transplanting to the field. As a consequence, hardening could promote growth and biomass gain during the initial development of C. arabica in the field. Thus, the less interrupted initial growth in a changing environment should confer higher flowering intensity in hardened than in control plants. The aim of this work was to verify if leaf gas exchange and Ψleaf behaviour of C. arabica saplings grafted on C. canephora showed consistent alterations during hardening by WCs and if this was effective to improve vegetative and reproductive growth under field conditions. For these reasons, saplings of the Mundo Novo cultivar of C. arabica grafted on C. canephora were submitted to seven WCs over 35 days. Each WC was completed when net photosynthesis was close to zero. The pattern of leaf gas exchange, mainly stomatal conductance (gs), was modified permanently after three WCs and the new pattern of leaf gas exchange could result in a more positive water balance and less interrupted development of C. arabica saplings in the field, particularly due to permanent low values of gs. After field transplantation, hardened plants showed greater height and stem diameter, more leaves and branches, and superior biomass production in leaves, stem and roots than control plants in dry and wet periods. The number of flowers was also significantly higher in hardened than in control plants. On the other hand, similar values were found between control and hardened plants in the leaf area ratio and the shoot/root ratio. Therefore, previous hardening by WCs was effective in improving leaf gas exchange, vegetative and reproductive development under field conditions and maintained the original biomass partitioning among the main plant compartments in dry and wet periods.

The effects of day length extension and night interruption on flowering responses of St John's Wort (Hypericum perforatum) plants were investigated. Field-grown plants were subjected to five different day lengths (11, 13, 15, 17 and 19 h d−1) or night interruption for 70 days. The results indicated that St John's Wort is a long-day plant requiring a critical day length of 15 hd−1 for flowering induction. Both day length extension (duration longer than 15 h) and night interruption, with artificial light (fluorescent lamps that delivered 30 μmol m−2 s−1 photosynthetic photon flux density at plant height) were effective for flowering induction and seed setting. Day length extension or night interruption experienced by the maternal plant also affected the germination responses of the seeds produced. Plants that had received 19 h of day length treatment produced seeds with better germination responses. Night interruption with daylight type fluorescent lamps was also effective for producing relatively high quality seeds, although these seeds had slightly lower germination rates and longer mean germination time than seeds produced under 19 h of day length. Such a night interruption system could be considered for seed production of St John's Wort on a commercial scale.

We demonstrated experimentally that coconut husk ash is an excellent mineral fertilizer for immature coconut hybrids on developed peat, providing potassium (K) in particular. Coconut husk ash performed as well as potassium chloride (KCl) in a proportion of 2–2.5 to 1. At four years, 99% of coconut palms fertilized with husk ash, 92% of coconut palms fertilized with KCl and 26% of control palms were sexually differentiated. The cumulative yield in the first two harvesting years more than trebled between control palms (26 nuts per tree) and the palms fertilized with KCl (93 nuts per tree) or husk ash (105 nuts per tree). This is an important result, given the intensity of K deficiency and the increasing cost of imported fertilizers. Although coconut husk ash will never totally replace K fertilizer, it can recycle a substantial proportion of nutrients in a coconut plantation. It now remains to optimize its use on an estate level, by examining the feasibility and cost-effectiveness of its mass production and determining conditions for maximum efficiency.