During the Phase II of the HarvestZinc project, different fertilizer trials were conducted in seven participating countries. Studies focused on the ''mega-crops'' wheat and rice and included sorghum and common bean. Wheat experiments were established in Turkey, China, India, Pakistan and Zambia; rice experiments in China, Thailand and India; common beans studies in Brazil, and sorghum experiments in addition to wheat in Zambia.
The 2nd Phase of the project developed under HarvestPlus umbrella was also supported by:
Mosaic Company, USA
- K+S KALI GmbH, Germany
- International Zinc Association, Belgium
- OMEX Agrifluids, England
- International Fertilizer Industry Association, France
- International Plant Nutrition Institute, USA
- Bayer CropScience, Germany
- ADOB, Poland
- Valagro, Italy
- FBSciences, USA
- ATP Nutrition, Canada
Major results, accomplishments, and lessons learned in the 2nd Phase of the HarvestZinc project are summarized below:
EFFECT OF ZINC APPLICATION ON GRAIN YIELD
Field experiments revealed a large variation for grain yield response to Zn fertilization among countries and among the locations of a given country for cereals wheat, rice and sorghum and the legume crop common bean.
Soil Zn applications significantly increased wheat grain yield in India and Pakistan, while in Turkey, China, and Zambia increases were minor. Rice trials were conducted in China, India and Thailand. On average, rice grain yield increased by soil Zn applications in all 3 countries, although increases in grain yield varied between years and locations. For common bean experiments in Brazil and sorghum trials in Zambia the effect of soil Zn fertilization on grain yield was inconsistent between years and locations. In the trials, attention has been also given to the role of high seed-Zn on grain yield.
For wheat, combining data across the major wheat-growing countries India, Pakistan, China and Turkey and cropping years, soil Zn application and using Zn-enriched seeds improved wheat grain yield in 19 locations by 7.6% and 4.8%, respectively. For rice, analyses across 14 Asian locations in India, China and Thailand revealed increases in grain yield by 6.2% and 4.0% for soil Zn application and Zn-enriched seeds, respectively.
EFFECT ON GRAIN ZINC CONCENTRATIONS
In contrast to the variation in grain yield among countries and within countries, results with grain Zn concentrations were more consistent. Grain Zn concentrations were strongly affected by foliar Zn applications, while soil Zn application was less effective. On average across experiments in Turkey, China, India, Pakistan and Zambia, soil ZnSO4 application resulted in a 4ppm increment in grain Zn for wheat; for rice, across experiments conducted in China, India and Thailand, the increment was 2ppm measured in brown rice. Similarly, soil Zn treatments caused only minimal increases in grain Zn concentration of sorghum and common bean.
Foliar Zn application increased grain Zn considerably and significantly: a single spray of ZnSO4 resulted in a net increase of 7 ppm in grain Zn of wheat based on data from 5 countries and 19 locations. Increase in grain Zn exceeded 10ppm and reached up to 13ppm (i.e., 42% increases) by applying certain commercial foliar Zn fertilizers from different companies. Applying Zn to foliar twice (at heading and early milk stage) resulted in further increases in grain Zn (up to 2-fold!) as reported in the first phase of the project. Positive effects of foliar Zn application on grain Zn was substantially further increased by i) adding an acidifying compound, ii) by inclusion of urea, and iii) by including an adjuvant/tenside in the spray solution and iv) by the application timing.
Rice showed less response to foliar Zn fertilization when compared to wheat. A single spray of ZnSO4 to rice in China, India and Thailand across 14 locations resulted in an average increase of 4ppm (20 % increase) in brown rice. The increases in grain Zn in bean and sorghum were 6ppm and 7ppm by a single Zn spray, respectively. Certain commercial foliar fertilizers had higher impact on grain Zn, resulting in 11ppm net increments in grain Zn in bean and sorghum.
IMPACT OF HIGH SEED-ZINC ON SEEDLING GROWTH
The effect of Zn-enriched seeds on seedling development and stand establishment was also evaluated by measuring the number of emerged plants and seedling height during early growth stage. Using seeds enriched with Zn through foliar fertilization in the previous year had very positive effects on germination and seedling development of wheat in China and particularly in Pakistan. In India, there were also increases in seedling emergence due to seed Zn-enrichment, but the increases were not statistically significant. Detailed results will be published in an international journal.
USE OF PESTICIDES WITH ZINC FERTILIZERS
One of the further important findings in the 2nd phase of the project was related to the applicability of foliar Zn fertilizers together with commonly used insecticides and fungicides. Corresponding experiments were conducted to examine whether the use of ZnSO4 together with widely used fungicides and insecticides negatively influences agronomic effectiveness of foliar Zn application.The field experiments were established in 12 locations on rice, 24 locations on wheat and 5 locations on common bean in 7 countries by using 14 different fungicides and insecticides. The results showed that increases in grain Zn with foliar Zn spray with or without pesticides (e.g., insecticides or fungicides) were almost similar. As demonstrated in this project, compatibly of fertilizer zinc and pesticides may encourage the farmers to add Zn in the pesticide spray solutions, as Zn fertilization may also contribute to better crop productivity besides enrichment of grain Zn.
VISIBILITY AND DISSEMINATION
"Zinc Days" Event
From the start of the second phase of the project, a total of 15 "Zinc Days" events have been organized in China, Pakistan, India, Thailand, Turkey, Zambia, Brazil and Mexico, and more than 3200 farmers and agronomists participated in these events. In Zambia, the number of the about 4000 participants attended to an annual field day in Lusaka in which the zinc day event was organized (see "Zinc Days" section)
PhD and MSc Students
Several MSc and PhD students are involved in this project and conducted their thesis projects capitalizing on trials of the HarvestZinc project. In total, 10 students carried out their thesis projects under HarvestZinc project.
HarvestZinc project was also active in publishing the project results in peer-reviewed international journals. To date, more than 25 research and review articles have been published in prestigious scientific journals. Most of them have already received very high citations (see Publications)