Maize cultivars response to saline irrigation scheduling

The cyclic strategy to use saline water can produce satisfactory yields for salt-sensitive maize than the blending strategy if only once irrigation is needed during the crop season. If more than twice irrigations are needed, it is preferable to alternate applications of poor quality and fresh water. A glass house study was conducted to investigate the effect of saline irrigation scheduling on different maize cultivars in 2007. Four maize cultivars from Pakistan salt- tolerant (EV-1098 and Agaiti-2002) and sensitive (EV-4001 and Akbar) were used in the experiment. Eight irrigation patterns based on canal irrigation and NaCl salinized water (EC 4.0 dS m-1) was applied at three crop growth stages. The treatments comprised: I1 =Irrigation by canal water during whole growing period, I2 = canal water for soaking and at early whorl stage and by saline water (EC 4.0 dS m-1) at the late whorl stage, I3=Irrigation by canal water for soaking and at late whorl stage and saline water at early whorl stage, I4 =Irrigation by saline water for soaking and by canal water at early whorl and late whorl stages, I5 =Irrigation by canal water for soaking and by saline water during the early whorl and late whorl stages, I6=Irrigation by saline water for soaking and at late whorl stage and by canal water at early whorl stage, I7 =Irrigation by saline water for soaking and at early whorl stage and by canal water at late whorl stage, and I8=Irrigation by saline water throughout growing period. Satisfactory maize growth and fodder yield was noted with application of canal water applied at all growth stages and treatments comprising canal water application at soaking, early whorl stage and brackish water (EC 4.0 dS m-1) during late whorl stage. Performance of maize cultivars under water scheduling revealed that EV-1098 and Agaiti-2002 responded well as compared to EV-4001 and Akbar. Both cultivars accumulated less Na+ and Cl- and maintained more K+, ultimately better K+/Na+ ratio

Effect of mixed organic-inorganic fertilizer on growth and phosphorus uptake of setaria grass (Setaria splendida).

Increasing phosphorus (P) availability in tropical P deficient soils is a challenging task. Vermicomposting of organic wastes in the presence of phosphate rock facilitates the release of P and this has the potential to address crop P needs. A study was conducted to assess and compare the effects of application of gafsa phosphate rock (GPR) alone and GPR in combination with empty oil palm fruit bunches, earthworms (Pontoscolex corethrurus), arbuscular mycorrhiza fungi (Glomus mosseae), and P-enriched vermicompost, in fulfilling the P requirements of the setaria (Setaria splendida L.,) grass. Application of mixed organic fertilizer combined with GPR was effective in increasing dry matter yield of grass, with 19% higher dry matter production as compared to the use of GPR alone. Among the organic fertilizers, application of P-enriched vermicompost was the best to support the grass growth. Nitrogen, P, Ca, and Mg uptake of the grass treated with P-enriched vermicompost was higher. Nitrogen and P utilization efficiency of the setaria grass treated with P-enriched vermicompost was also high. Residual P in soil treated with GPR was higher as compared to that treated with P-enriched vermicompost. However, plant available P was higher than that for the other GPR application techniques. The different types of earthworms had no effect on the quantum of nutrient uptake and the dry matter yield of the setaria grass. Application of a mixture of GPR and empty oil palm fruit bunch to the soil increased the dry matter of setaria compared to the use of inorganic fertilizer alone. We conclude that soil treated with P-enriched vermicompost was an efficient treatment for increasing availability of P (24.28 mg kg-1), N, P, Ca and Mg uptake (53.76, 41.83, 13.58 and 15.16 mg pot-1, respectively); which ultimately enhanced root volume (163 cm3) and dry matter yield (5.75 to 6.46 g pot-1)

Water quality effect on fodder maize and soil characteristics

The field experiment was conducted to observe the impact of different water qualities on salt- tolerant and sensitive maize cultivars at Sindh Agriculture University, Tandojam during Spring and Autumn seasons of 2006. Maize cultivars viz. tolerant (EV-1098, Agaiti-2002) and sensitive (EV-4001 and Akbar) were treated with water qualities viz. EC 0.40 (Canal water), 2.0, 4.0, 6.0 and 8.0 dS m-1. The applied saline water levels were prepared by mixing the canal water with poor quality tube well water (EC 11.00 dS m-1). Soil samples were collected from 0-15, 15-30, 30-45, and 45-60 cm for determination of physicochemical properties viz. Soil texture (pre sowing), pH, EC, SAR, soluble cations and anions. Tall plants, more green and less dry leaves per plant, higher green fodder yield, and dry fodder yield were recorded with the application of canal water having EC 0.4 dS m-1. Decreased values of all these traits recorded as the salinity level incre ased from EC 0.4 to 8.0 dS m-1. Among the cultivars, EV-1098 and Agaiti-2002 performed better under different water qualities as compared to EV-4001 and Akbar. Application of brackish water also significantly affected the soil chemical composition by enhancing EC, soluble sodium, and chloride contents in soil. It is concluded that application of canal water is suitable for maximum maize productivity with safeguard of soil profiles from further deterioration in terms of salt content. Alternate use of brackish water could be less than EC 4.0 dS m-1 and increase in EC beyond this level reduced maize fodder yield and degraded soil

Estimation of greenhouse gases emission from a rice field of Kelantan, Malaysia by using DNDC model

Global warming is the main cause of greenhouse gases (GHG) including carbon dioxide (CO2), methane (CH4) and nitrous oxide (N2O). The Denitrification and Decomposition (DNDC) model is considered a good tool to validate and estimate these gases from various agricultural practices. The farmers of Kota Bharu, Kelantan, Peninsular Malaysia grow rice in soils which has clay loam soil texture with 5.59 soil pH and 0.0193 kg ha -1 initial soil organic carbon. The farmers grow two rice crops by applying 248 kg N ha -1 year -1. The model validation was found satisfactory and gave correct simulations while comparing with other international modeled studies. The yearly DNDC simulation for CO2 flux rate was 4392 kg C ha -1, 33.7 N2O kg ha -1 year -1 with -2 CH4 flux. The Global Warming Potential (GWP) for CO2 flux was 16105 kg CO2-eq ha -1 and N2O of 16403 kg CO2-eq ha -1; however, CH4 was found as sink (-66 kg CO2-eq ha -1). Bulk of all these gases had 32442 kg CO2-eq ha -1 net GWP. The DNDC simulations of field uncertainties by N rates (20% less than recommended, recommended and 20, 40 and 60% more than recommended) and SOC rates at 0.04, 0.03, 0.02 and 0.0193 kg C kg -1) were run through linear correlation. The unit increase in N as well as SOC rates correspondingly increased NH3 volatilization by 4.09, 3.76, 2.31 and 1.28 kg N ha -1 year -1, respectively, N2O flux by 10.06, 6.80, 6.51 and 1.16kg N ha -1, respectively, NO flux by 0.76, 3.25, 3.14 and 2.03 kg N ha -1 year -1 and N2 flux by 17.87, 18.21, 21.75 and 25.22 kg ha -1 year -1, respectively. In conclusion, the validation of agricultural data through DNDC model was perfect. The ongoing agricultural practices in the area have been found contributing small quantities of CO 2 and N 2O except CH 4 which is serving as sink. In future, the increase in soil organic carbon as well as nitrogen rates probably may involve this area towards more GHG (CO2, N2O, CH4) emissions

Effects of earthworms, arbuscular mycorrhizae, and phosphate rock on setaria grass (Setaria splendida) and phosphorus availability in soil

Phosphate rock (PR) is essentially insoluble in water. Dissolution of PR under acidic soil conditions is a necessary pre-requisite for uptake of phosphorus (P) by plant. Improvement in P dissolution could be achieved through the interaction of micro- and macro-organisms in soil. A greenhouse pot experiment was conducted with epigeic earthworms (W) (Pontoscolex corethrurus M.), arbuscular mycorrhizae (AM) fungi (Glomus mosseae Tul), and gafsa phosphate rock (GPR) to evaluate their effects on dry matter (DM), root colonization, and nutrient accumulation of setaria grass (Setaria splendida) and availability of P in the soil. Earthworms significantly increased DM yield (23.3 g pot-1) and P accumulation (16 mg P pot-1) of setaria grass. The AM colonization on inoculated plants was high (81%) compared to earthworms. Accumulation of P, N, K, Ca2+ and Mg2+ in grass were significantly higher in soils contained earthworms, compared to other treatments. Presence of worm (W), AM, and GPR significantly increased phosphorus utilization efficiency (PUE) of setaria grass. The residual P was lower in the soils treated with worm or AM compared to non-treated (control) soil which might be due to higher P uptake by setaria grass. However, plant's available P increased under AM or W treatment. There was a significant interaction effect between AM, W and GPR on P accumulation of setaria grass indicating, efficiency of grass in taking up phosphorous. Thus, it could be concluded that presence of W, AM and GPR have efficiency to increase the amount of plant available P in soil

Estimation of nitrous oxide, carbon dioxide and methane emissions from selected rice soils in Malaysia using DNDC model

Greenhouse gases (GHG) such as carbon dioxide (CO2), methane (CH4) and nitrous oxide (N2O) are the main cause of global warming. In Malaysia, all these gases can be assessed through Denitrification and Decomposition (DNDC) model in various agricultural systems. Three soils and agriculture system studied for simulation were located in Kota Bharu (Kelantan) situated between 6°8′N 102°15′E, Alor Setar (Kedah) situated between 06°07'N,l 100°22'E and Selangor, Malaysia situated at 2°43′N 101°57′E. All the three sites have double cropping system in a year. The objectives of these studies were to examine and forecast the agricultural practices involved in N2O, CO2 and CH4 emissions from various rice fields and to utilize the modeling approach to estimate changes in N2O, CO2 and CH4 emissions from rice soils of Malaysia. Through DNDC model, four interacting sub-models: thermal/hydraulic, crop growth, decomposition, and denitrification were simulated. (Rice cultivation is an important source of GHGs that cause global warming. Rice systems contribute over 25% of total global anthropogenic CH4 emissions currently). The model efficiently treats nitrogen inputs from atmospheric deposition, fertilizer use and nitrogen fixation and represents soil inorganic turnover to enable calculation of gas emissions. The farmers of Kelantan, Kedah and Selangor apply 248, 280 and 300 kg N ha-1 year-1,respectively. The model validation was found satisfactory and gave correct simulations when compared with other studies reported elsewhere. In Kelantan,simulated CO2 flux rate was 4392 kg C ha-1, 33.7 N2O kg ha-1 year-1 with -2CH4 flux kg ha-1 year-1. The Global Warming Potential (GWP) for CO2 flux was 16105 kg CO2-eq ha-1, N2O 16403 kg CO2-eq ha-1. However, CH4 was found as sink (-66 kg CO2-eq ha-1). Bulk of all these gases had 32442 kg CO2-eq ha-1 net GWP. In Kedah, the simulated CO2 flux rate was 4675 kg C ha-1 and 15.2 kg N2O ha-1 year-1 recording -3 CH4 flux kg ha-1 year-1. The GWP for CO2 flux was 17141 kg CO2-eq ha-1, N2O 454412 kg CO2-eq ha-1. However, CH4 was found as sink (-92 kg CO2-eq ha-1) and thus, bulk of all these gases had 471460 kg CO2-eq ha-1 net GWP. In Selangor, CO2 flux rate was 1489 kg C ha-1, 152.1 N2O kg ha-1 year-1 with -2 CH4 flux. The GWP for CO2 flux was 5460 kg CO2-eq ha-1 and N2O 74085 kg CO2-eq ha-1. However, CH4 was found as sink (-66 kg CO2-eq ha-1). Bulk of all these gases had 79440 kg CO2-eq ha-1 net GWP. The simulations for field uncertainties were tested with variable nitrogen rates at 20% less than recommended and 20, 40 and 60% more N than recommended along with soil organic carbon (SOC) rates at 4, 3, 2 and 1.93% kg C kg-1 in Kelantan, 2, 3, 4 and 5% SOC rates in Kedah and 2.31, 3, 4 and 5% in Selangor. In all the rice sites, the unit increase in N rate as well as SOC correspondingly increased N2O flux by 10.06, 6.80, 6.51 and 1.16 kg N ha-1. NO flux by 0.76, 3.25, 3.14 and 2.03 kg N ha-1 year-1.N2 flux 17.87, 18.21, 21.75 and 25.22 kg ha-1 year-1. N2O GWP flux rate by 3495.3, 1614.6, 6.3.0 and 499.4. In Kedah, the unit increase in N rate as well as SOC correspondingly increased N2O flux by 0.25, 0.42, 2.51 and 0.96 kg N ha-1, NO flux by 1.04, 1.17, 1.33, 1.51 kg N ha-1 year-1 and N2 flux by 0.12, 0.83, 1.19 and 0.99 kg ha-1 year-1. N2O GWP flux rate by 30.6, 23033, 110302 and 154765. Similarly, in Selangor, the unit increase in N rate as well as SOC correspondingly increased N2O flux by 2.86, 3.83, 7.61 and 1.95 kg N ha-1. NO flux by 5.41, 5.0, 4.39 and 3.78 kg N ha-1 year-1. N2 flux by 5.22, 9.76, 18.46 and 30.44 kg ha-1 year-1. N2O GWP flux rate by 1385.3, 1865.3, 2701.5 and 3411.5. In conclusion, the DNDC model validations were accurate for Malaysian rice. The farmers of these three sites are applying more nitrogen fertilizer against the crop demand corresponding more yearly NH3 volatilization loss and increased fluxes of N2O, NO and N2 in the environment and excess fertilizer leach down in the soil by polluting underground water. In Malaysian rice, the simulated CH4 values were negative indicating it as sink. In these sites, the GWP is also increasing due to elevated CO2, ongoing management practices especially cropping system, straw incorporation, irrigation/flooding and N fertilizer management as well as C storage potential of the soil which is increasing with the passage of time due to left over residues and soil flooding condition. The DNDC, was modified to enhance its capacity of predicting GHG emissions from rice ecosystems. The major modifications focused on simulations of anaerobic biogeochemistry and rice growth as well as parameterization of rice management. The new model was tested for its sensitivities to management alternatives and variations in natural conditions including weather and soil properties. The test results indicated that (1) varying management practices could substantially affect CO2, CH4, or N2O emissions from rice; (2) soil properties affected the impacts of management alternatives on GHG emissions; and (3) the most sensitive management practices or soil factors varied for different GHGs. For estimating GHG emissions under certain management conditions at regional scale, the spatial heterogeneity of soil properties (e.g., texture, SOC content, pH) are the major source of uncertainty

Seasonal Evaluation of Trace Metals in Irrigated Soils at Various Sites in Phuleli Command Area (Sindh), Pakistan

Phuleli Canal (Sindh) Pakistan is the main source of irrigation water for lower Sindh. However, its quality has been deteriorated by the addition of industrial effluents and city wastes discharged directly or indirectly into canal when it passes through Hyderabad city. For monitoring the effect of this canal water on soil quality of the command area, the present study was designed to evaluate the seasonal variability of trace metals including Cu, Fe, Zn and Mn in the cultivated soil area. The soil samples were collected from different seven sites (reduced distance, RD = 304.8 m) RD-0, RD-30, RD-50, RD-70, RD-90, RD-110 and RD-130) in four seasons (summer, autumn, winter, and spring) and analysed for Cu, Fe, Zn and Mn contents. Then, the obtained results were compared with the maximum permissible values of FAO for agriculture/crop production. Results showed that the Zn contents in soil samples was relatively higher than FAO permissible limits during winter in all soil layers and all sites mostly at upper reach sites of Phuleli Command area. While, the Fe content in soil at all depths was found higher during winter, autumn and spring. Whereas, in summer season it was relatively more in upper soil layers near mid to down reach sites and were not within the permissible limits of FAO. Same was true with Cu and Mn which were also not within the permissible limits of FAO for crop production. So, it was inferred that almost of the locations trace elements in soils found higher under Phuleli Canal Command area were mainly produced from various pollution sources viz, industrial and municipal liquid effluents

Response of Conjunctive Use of Fresh and Saline Water on Growth and Biomass of Cotton Genotypes

A pot experiment was conducted to study the effects of conjunctive use of saline and fresh water on the growth and biomass of cotton crop and to observe varietal variability for salinity tolerance and ion contents of cotton genotypes. Four cotton genotypes (Sindh-1, BT-121, CRISS-494, CRISS-588) were irrigated with four treatments, C1 (control+ tape water), C2 (EC 4.0 dS m-1, throughout growth period), ( (six irrigation with C2 + six irrigation with C1), C3 (EC 8.0 dS m-1, throughout growth period), (six irrigation C1+ six irrigation C3), (six irrigation C3+ six irrigation C1), C4 (EC 12.0 dS m-1, throughout growth period), (six irrigation C1+ six irrigation C4). The results showed that highest fresh biomass, plant height, number of leaves plant-1, number of bolls and boll weight was obtained in the treatment where tape water was used. Whereas, these parameters were decrease significantly with the increasing salinity levels from 4 to 12 dS m-1 and when saline water was applied continuously throughout growth period. The cotton genotypes Sindh-1 and Bt-21 performed well under conjunctive use of saline and fresh water with maximum values in compare to genotypes CRIS 494 and 588. The Na+ and Cl- accumulation in cotton leaves and in soil significantly increased with rising EC levels of irrigation water. However, Na+ and Cl- contents were found more in CRIS 494 and CRIS 588 than Sindh-1 and Bt1. It is concluded that Sindh-1 and Bt-121 may be cultivated in saline areas with alternate irrigation

Consequences of micronutrient coated urea for maximizing N-uptake

Nitrogen (N) losses from agricultural fields are commonly observed particularly from urea. To minimize ammonia (NH3) voltalization the micronutrient coated urea is applied to enhance N-efficiency. This study is an application of micronutrient coated urea with zinc (Zn) and copper (Cu) for two soil series of Malaysia. A laboratory experiment was designed according to the force draft technique for trapping the NH3 loss. The results manifested the rate of ammonia voltalization is 16% for uncoated urea and 8% for coated urea with micronutrients during first two weeks of the observation. It was observed that the ammonia loss gradually decreased with the time for both soil series. The mean comparison has shown the positive effect of Zn and Cu coated urea in comparison with the other treatments. The overall results revealed the efficacy of micronutrient coated urea on both soil series to maximize N-uptake and reduce NH3 voltalization

Distribution of Halophyte Plants in Relation to Properties of Salt-Affected Soils of District Thatta

The main objective of this study was to survey and collect some halophyte species capable of growing in highly salt affected soils and their distribution in relation to some soil properties of district Thatta. Sueda fruticosa, Tamarix aphylla, Ceriops candoleana, Cynodon dactylon, and Chenopodum album species were collected form Thatta. Soil samples were collected from the vicinity of each halophyte and were analyzed for pH, organic matter (OM), electrical conductivity (EC), soluble Na+, Ca2+, Mg2+, HCO3-, Cl-, sodium absorption ratio (SAR), and exchangeable sodium percentage (ESP). Halophytes species collected were analyzed for ion (Na+, K+, Ca2+, Mg2+and Cl-) contents. Data regarding plant ionic composition showed that contents of Na+ ranged between 3.7-6.9 %, K+0.7-1.9 ,Ca+2 0.4--1.2 %, Mg2+ 0.6-2.2 and Cl- contents between 0.1-0.8 in species collected from Thatta, respectively. Data further revealed that maximum Na+ (6.9 and %) was recorded in Sueda fruticosa and Salsola indica, highest K+(1.9 %) was noted in Chenopodium album species, greatest Ca+2 (1.2 %) was documented in Sueda fruticosaspecies, highest Mg2+ (2.2 %) was observed in Sueda fruticosa whereas, maximum Cl- (0.8 %) was noted in Sueda fruticosa collected from district Thatta, respectively. Data pertaining to soil properties indicated that EC of studied soils ranged between 7.0-18.4dS m-1, pH 7.5-8.0. O.M 0.82-0.94 % , soluble Ca2+ 17.3-33.3 meq L-1, Mg2+ 15.5-24.6 meq L-1, Na+ 43.6-83.4 meq L-1 , Ka+ 3.20-4.50 meq L-1, HCO3? 2.4-5.3 meq L-1, Cl- 55.6-145.4 meq L-1, SAR 10.2-17.1 whereas, ESP ranged between 12.2-19.6 % in soil samples collected from Thatta, respectively. It was concluded that halophyte species Sueda fruticosa, Tamarix aphylla, gallica, Salsola indica, Cyperus irria accumulate significant amounts of salt (Na+ and Cl-)from salt-affected soil and, therefore, may remediate land to the point where native plants could invade and become established, or the site could be returned to agricultural productivity. These halophytes species have an excellent potential for rehabilitation of degraded salt affected soils