Ridzwan A. Halim

Impact of organic and inorganic fertilizers on the yield and quality of silage corn intercropped with soybean

Background Corn silage is an important feed for intense ruminant production, but the growth of corn relies heavily on the use of chemical fertilizers. Sustainable crop production requires careful management of all nutrient sources available on a farm, particularly in corn-based cropping systems. Methods Experiments were conducted to determine the appropriate technique of corn-legume intercropping in conjunction with the supplemental use of chemical fertilizers, organic manure, and biofertilizers (BFs). Acetylene reduction assays (ARAs) were also performed on corn and soybean roots. Results Combining chemical fertilizers with chicken manure (CM) in a 50:50 ratio and applying 50% NPK+50% CM+BF produced fresh forage and dry matter (DM) yields that were similar to those produced in the 100% nitrogen (N), phosphorus (P), potassium (K) treatment. Among the lone fertilizer treatments, the inorganic fertilizer (100% NPK) treatment produced the highest DM yield (13.86 t/ha) of forage and outyielded the 100% CM (9.74 t/ha) treatment. However, when CM was combined with NPK, the resulting DM yield of forage (13.86 t/ha) was the same as that resulting from 100% NPK (13.68 t/ha). Compared with CM applications alone, combinations of NPK and CM applications resulted in increased plant height, crop growth rates (CGRs) and leaf area index (LAI), but the values of these parameters were similar to those resulting from 100% NPK application. Fertilizers in which the ratio was 50% CM+50% NPK or 50% CM+50% NPK+BF resulted in protein yields that were similar to those resulting from conventional fertilizers. Similarly, the CP content did not significantly differ between applications of the 100% NPK and 50% CM+50% NPK fertilizers. The use of BFs had no significant impact on improving either the yield or quality of forage fertilized with inorganic or organic fertilizer. Lactic acid responded differently to different fertilizer applications and was significantly higher in the fertilized plots than in the unfertilized plots. Compared with treatments of lone chemical and lone organic manure fertilizers, treatments involving applications of BF and a combination of BF and NPK or CM resulted in higher ARA values. Discussion There is no simple and easy approach to increase biological nitrogen fixation (BNF) in grain legumes grown as part of a cropping system under realistic farm field conditions. Overall, evidence recorded from this study proves that, compared with corn monocrops combined with CM and chemical fertilizers, corn-soybean intercrops could increase forage yields and quality, produce higher total protein yields, and reduce the need for protein supplements and chemical fertilizers.

Potential of four corn varieties at different harvest stages for tropical silage production in Malaysia

Objective Apart from various climatic differences, corn harvest stage and varieties are two major factors that can influence the yield and quality of corn silage in the tropics. A study was conducted to determine the optimum harvest stage of four corn varieties for silage production in Malaysia. Methods Corn was harvested at four growth stages; silking, milk, dough, and dent stages from four varieties; Sweet Corn hybrid 926, Suwan, breeding test line (BTL) 1 and BTL 2. Using a split plot design, the treatments were then analysed based on the plant growth performance, yield, nutritive and feeding values followed by a financial feasibility study for potential commercialization. Results Significant differences and interactions were detected across the parameters suggesting varying responses among the varieties towards the harvest stages. Sweet Corn was best harvested early in the dough stage due to high dry matter (DM) yield, digestible nutrient, and energy content with low fibre portion. Suwan was recommended to be harvested at the dent stage when it gave the highest DM yield with optimum digestible nutrient and energy content with low acid detergent fibre. BTL 1 and BTL 2 varieties can either be harvested at dough or dent stages as the crude protein, crude fibre, DM yield, DM content, digestible nutrient and energy were not significantly different at either stage. Further financial analysis showed that only Sweet Corn production was not financially feasible while Suwan had the best financial appraisal values among the grain varieties. Conclusion In conclusion, only the grain varieties tested had the potential for silage making according to their optimum harvest stage but Suwan is highly recommended for commercialization as it was the most profitable.

Physiological Adaptation of Alfalfa Genotypes to Salt Stress (One of Deleterious Impacts of Climate Change)

Plant physiological processes are invariably linked to the deleterious influences of climate change. This study seeks to identify the physiological responses of some salt tolerant ecotypes of alfalfa when exposed to salt stress during the mature phase of growth. Five Iranian alfalfa ecotypes representative of three climatic zones were evaluated for their response to salt stress in a split plot trial, with three replications, where the main plots were five ecotypes and subplots were the levels of salinity. The seeds were planted in plastic pots filled with sand and immersed in nutrient solution. After more than 2 months when the plant became mature the EC of nutrient solution was increased gradually by adding sodium chloride. At every 15 days the EC increased by 3 dS m−1, and the final EC was 18 dS m−1. The EC at each stage of salt addition was 6, 12, and 18 dS m−1. At each stage of salinity the physiological characteristics of alfalfa ecotypes were measured including: crop growth rate, photosynthesis rate, chlorophyll content, stomatal conductance, and chlorophyll fluorescence. The results showed that the physiological parameters were affected by salt concentration and there were varying responses between genotypes. Salt stress resulted in a linear decline in the photosynthetic rate from 21 μmol CO2 m−2 s−1 in control to 5 μmol CO2 m−2 s−1 at 18 dS m−1. Ecotypes showed similar responses in photosynthesis and stomatal conductance under salt stress. A positive correlation between CO2 net uptake and stomatal conductance was observed. The chlorophyll content decreased with increasing salinity and there is a significant difference between ecotypes in terms of chlorophyll content. The results of Fv/Fm, ratio showed that up to 12 dS m−1 there were not significant changes in Fv/Fm ratio but after 12 dS m−1 the Fv/Fm ratio decreased with increasing of salt stress. There was a significant difference in Fv/Fm ratio among the ecotypes with increasing salinity. The study indicated that physiological responses to salinity varied among ecotypes, indicating genotypic differences in salt tolerance. In terms of physiological response the ecotype Ghargholough was identified as the most salt tolerant and should be chosen for areas that have become saline as a result of climate change.