PLANTING CALENDARS: DEVELOPMENT BASED ON AGRO-CLIMATIC INDICES, WATER AVAILABILITY AND AVOIDANCE OF PESTS & ADVERSE CONDITIONS

Transcription

1 Philippine Journal of Crop Science (PJCS) August 2005, 30(2): Copyright 2005, Crop Science Society of the Philippines Released 19 June 2005 PLANTING CALENDARS: DEVELOPMENT BASED ON AGRO-CLIMATIC INDICES, WATER AVAILABILITY AND AVOIDANCE OF PESTS & ADVERSE CONDITIONS PC ALQUIZA, RC CASTRO, ND GANOTISI, FS BAYSAC, JM MALOOM & RT TUMBAGA Philippine Rice Research Institute, Batac, Ilocos Norte 2906, Philippines The optimized planting calendars of 5 cropping patterns (rice-pepper-corn relay, rice-corn-onion, rice-mungbean+corn-corn, ricemungbean-mungbean+corn and rice-onion-mungbean+corn), were developed, based on agro-climatic indices, water availability and avoidance of pests. The study was conducted at the PhilRice Experimental Farm in Batac for 2 years and the planting calendars were verified in farmers fields in 2 municipalities of Ilocos Norte (Batac and Currimao), and 1 municipality in La Union (Bacnotan). Groundwater availability, pests and disease occurrences and soil fertility status were periodically monitored. The results indicate that the income performance of planting calendars depends on the geographical location; that is to say, different sites and different cropping patterns require different planting calendars. Thus, in Batac, the rice-pepper-corn relay for the months of June to May gave the highest net income of P110,346/ha/year. In Currimao, rice-corn-onion-corn grown from June 15 to April had the highest net income (P107,901/ha/year). In Bacnotan, the rice-corn-onion pattern set from June to April obtained the highest net income (P134,497/ha/year). Populations of insects and disease vectors were minimal. The continuous rotation of crops also suppressed the growth of weeds. In rainfed areas, the groundwater can still support crop production from January to March. Through mulching and other water conservation techniques, planting can be further extended up to May. A tremendous decrease in soil organic matter content was noted with continuous cropping. Hence, supplemental application of organic fertilizers is recommended to make the soil sustainable for crop production. agro-climatic indices, corn, cropping patterns, green corn, mungbean, net income, onion, pepper, planting calendar, rice, water availability, water conservation INTRODUCTION Farmers in the Ilocos Region are mostly tenants tilling relatively small pieces of land. Hence, whatever small produce they get from the small farms has to be shared with the landlord. To provide a decent income for their big families, the farmers must intensively utilize the land by planting more than 2 crops per year. Cropping intensification, however, is constrained by the availability of moisture in these mostly rain-fed farms. With the short but torrential rainy seasons and long drought-prone summers, the choice of crops to grow and the corresponding timing of planting become critical. Improper choices and timing expose the crops to risks such as drought, typhoons and other adverse weather conditions, as well as pests and diseases. These risks, however, can be mitigated through correct advisories to the farmers. Weather forecasts, the determination of return periods of adverse weather conditions, seasonal characteristics of surface and ground waters, the epidemiology of pests and diseases as well as the water requirements of specific crops in the cropping system, are vital inputs for such advisories. We have found that these advisories can be incorporated in a planting calendar as a general guide for farmers. In the Ilocos Region, farmers have been practicing various crop rotation schemes for years. Planting upland crops after wetseason rice is commonly practiced (Francisco 1995). Farming is highly intensive, diversified, and commercialized. The cropping system is predominantly rice-based in the wet season and highvalue cash crops are grown during the dry season (IRRI 1991). A wide range of crops can be grown after rice depending on rainfall and availability of water, elevation and land features of the environment. The major crops planted after rice include corn, tobacco, garlic, and legumes. High-value crops like melon, pepper, tomato, onion, corn, tobacco and other vegetables are also widely grown after rice. These crops are preferably grown during the month of October to November because of their high

2 profitability. An intensified, diversified and commercialized system, however, is oftentimes exposed to several risks. This includes the risk of adverse climatic conditions (Francisco 1995), as well as inappropriate crop selection, which can be affected by market forces and the occurrence of pests and diseases. In the Ilocos Region, and other regions with similar conditions, rainfall is a major climatic factor that determines crop productivity. Considering this, the development of workable planting calendars for rice and other crops raised after rice is necessary for improved crop production overall. Earlier, Ganotisi et al (2002) reported that among the agroclimatic indices that bear much significance to growing crops are dry weather harvest reliability, sunshine reliability, drought and excessive rainfall hazard, weekly rainfall and number of rainy days, and the onset of the rainy season. Subsequently, the results of their study became the bases for the development of cropping calendars for the rainfed areas of Northwestern Luzon, particularly, Ilocos Norte. Proceeding from the above, the objectives of the current study were as follows: 1. To characterize the agro-climatic patterns of selected rice and rice-based areas in selected towns in the Ilocos Region. 2. To determine appropriate crop sequences based on water availability, soil fertility and occurrences of pests, diseases and other adverse conditions. 3. To develop planting calendars based on the above. 4. To determine the economic profitability of cropping sequences following the planting calendars. 14 MATERIALS & METHODS A. Collection & analysis of weather data The 20-, 25- and 10-year rainfall data from the data banks of PAGASA Laoag City, PAGASA MMSU (Batac, Ilocos Norte) and PAGASA Vigan City (Ilocos Sur), respectively, were analyzed for their agro-climatic indices. The indices included probability of rainfall occurrence, dry weather harvest reliability (DWHR), sunshine reliability (SR), drought hazard (DH), excessive rainfall hazard (ERH), weekly rainfall and number of rainy days per week, and onset of rainy season. These indices became the initial basis for the development of planting calendars for the service areas of these weather stations. B. Identification and documentation of dominant cropping patterns The different cropping patterns used by the farmers in the Ilocos Region were identified through a consultation workshop. The dominant cropping patterns were rice-mungbean, rice-garlic, rice-onion, rice-corn and rice-vegetables. These were the bases for the formulation of the cropping patterns tested in the project. The recommended package of technologies for the different crop components were initially employed and later modified whenever necessary. C. Conduct of on-station trials With the agro-climatic indices and the dominant cropping patterns as bases, the following cropping patterns were tried onstation: 1. Rice-finger pepper-corn 2. Rice-green corn-onion 3. Rice-mungbean+corn (intra-row)-corn 4. Rice-mungbean-mungbean+corn 5. Rice-onion-mungbean+corn Each of the five cropping patterns was tested on-station in a 500 m 2 plot established at the Aracua Experimental Farm in Batac, Ilocos Norte. D. Verification in farmers fields The five cropping patterns were verified in Currimao, Ilocos Norte and Bacnotan, La Union. In the absence of on-site weather data for Bacnotan, the planting calendars for the cropping patterns were based on the weather data taken from PAGASA Vigan City, the nearest source. The recommended package of technologies for the different crop components were strictly employed and properly documented. The planting schedules as well as the growth and development of each crop component per cropping pattern were also properly recorded. The cropping patterns verified were the following: For Currimao, Ilocos Norte: 1) rice-finger pepper-corn relay 2) rice-onion-corn 3) rice-mungbean+corn (intra-row)-corn 4) rice-mungbean-mungbean+corn 5) rice-onion-mungbean+corn. For Bacnotan, La Union: 1) rice-finger pepper-corn relay 2) rice-green corn-onion 3) rice-mungbean+corn (intra-row)-corn 4) rice-mungbean-mungbean+corn 5) rice-onion-mungbean+corn. E. Data gathered The following data were gathered: (a) rainfall and (b) groundwater availability. The groundwater level was monitored twice a month from 2001 to The trend of the water level was plotted on a yearly basis. Also gathered were: (a) yield data of the different crop components, (b) pest and disease occurrences per crop component, (c) initial and final soil fertility status (ph, organic matter, N, P, K), and (d) labor and input utilization. Planting Calendars: Development Based On Agro-Climatic Indices

3 RESULTS & DISCUSSION Trials in Batac and Currimao, Ilocos Norte The planting calendars developed for the 5 cropping patterns are shown in Figure 1. These should be applicable in the southern towns of Ilocos Norte with the same ecosystem, namely San Nicolas, Batac, Paoay, Currimao, Pinili and Badoc. The results indicate that planting of rice should start during the month of June when there is abundant rainfall. The slight rainfall occurring thereafter enhances the growth and development of the rice crop. The abundant rainfall during the tillering stage up to early reproductive stage (July to August) favors weed control while providing sufficient water for the crop. Rainfall then decreases until the fourth week of September to October, which favors harvesting and drying. The months of October to December are recommended for the planting of upland crops like pepper, mungbean, corn and onions. These months are ideal for growing those crops because there is enough sunshine favorable for the plants to manufacture their own foods. Likewise, October to December and January to April are periods of favorable dry weather for harvesting upland crops. It was observed that the planting calendars of these cropping patterns were almost similar for 3 consecutive years. Hence the calendar can serve as basis for farmers in planting crops like onion, corn, pepper and mungbean. In those 3 years, the rice crops had avoided the typhoons that occurred during the months of September and October. During the dry seasons, the upland crops had avoided the drought conditions because the groundwater was the source of irrigation for the crops planted between the months of February and March. Groundwater availability The high probability of drought hazard in the months from January to April and from November to December necessitates the pumping of groundwater to support the crops grown during the months from January to April and from October to December. In terms of groundwater availability, the static water during the month of January is 1.83 meters below the ground surface (mbgs). The average rate of wellwater depletion is 1.2 cm per day (Figure 2). The wellwater transmissivity is low because it cannot recharge easily during pumping especially when most of the farmers withdraw water at the same time. This situation does not permit planting of 4 crops per year. However, if water conservation practices are employed like mulching, coupled with relay cropping, 4 crops can be grown in a year. Probability, %; Rainfall, mm Number of Rainy Days Month/Week PC Alquiza et al 15

4 It was noted that starting June, there was an increase in water level due to recharging of the wellwater, which was primarily due to the occurrence of heavy rains. Well-water recharging started from mid-may and occurred up to August, then leveled-off for about 3 months. Starting November, there was a gradual decrease in water level due to continuous pumping of water for irrigation of upland crops. For the 3-year duration of the project, the characteristics of the wellwater table were almost similar in both on-station (Batac) and farmers fields (Currimao and Bacnotan). This suggests that the groundwater can support crop production during the driest months of the year, which can permit planting of third and fourth crops. The fourth crop can be established but in limited areas. The recharging of wellwaters during mid-may can permit the establishment of the rice crop early. Groundwater can be used to supplement irrigation for the sowing of rice seeds and maintenance of the seedlings. stage while pod borer was abundant during the pod-formation and pod-filling stages. Aphids were observed on pepper during the vegetative stage while the ladybird beetle was present in all growth stages. Thrips were observed on onion at bulb formation. In general, it was noted that there was no dangerous build-up of insect populations in the different cropping patterns probably due to the rotation of crops, which resulted in the disruption of the life cycles of insects. In terms of diseases, bacterial leaf blight and sheath blight were observed in rice, while mungbean was infested with bean rust during the pod-filling stage. The presence of dew in the months of December and January enhanced the occurrence of these fungal diseases. Their late occurrence, however, did not affect the yield of mungbean. Leaf curling in onion and pepper, which were caused by thrips and aphids respectively, were observed during the early vegetative stages. Leaf curling was controlled with the application of insecticide to control the vectors. The most prevalent weeds observed were Cyperus, Portulaca and Echinochloa species. Portulaca was the most abundant and prevalent during the dry season starting January. Continuous cultivation and crop rotation controlled the build-up of the weed population. Soil fertility status At the start of the project, the initial soil organic matter (OM) content ranged from 2.23 to 2.62%. After 3 years of continuous cropping, a significant decrease in OM for all cropping patterns was observed (Table 1). The rice-mungbean+corn-corn pattern depleted the OM faster, with only 1.25% remaining. The riceonion-corn pattern, in contrast, had an OM of 2% after 3 years of Table 1. Soil fertility status of the different cropping patterns (PhilRice Batac. CY 2003) Cropping Patterns ph % OM P (ppm) K (ppm) Initial Final Initial Final Rice-pepper-corn relay Rice-corn-onion Rice-mungbean+corn-corn Rice-mungbean-mungbean+corn Rice-onion-mungbean-corn Insect pests and diseases The most common insect pests observed of the different crops planted were whorl maggots, leaffolders, grasshoppers, beanfly, aphids and thrips. In rice, whorl maggots, leaffolders and long-horned grasshoppers were present during the vegetative growth stage while rice bugs were abundant during the milking stage. Nonetheless, the populations of these insect pests were minimal and did not cause pest pressure that adversely affected yield. This was observed both in Batac (on-station) and in farmers fields (Currimao, Ilocos Norte and Bacnotan, La Union). The corn borer was dominant in corn, with the highest population noted during February planting, particularly in the ricecorn-corn pattern. This period favors the multiplication of the insect pests. But with proper crop rotation, the population build-up of this insect pest can be minimized. In mungbean, beanfly was common during the seedling 16 continuous cropping. This could be explained by the incorporation of the rice straw mulch used in onion. For all cropping patterns, the decrease suggests that there is faster turnover of soil OM. The continuous cultivation may have Planting Calendars: Development Based On Agro-Climatic Indices

5 promoted greater aeration, thus stimulating more microbial activities in decomposition. The phosphorous content was almost depleted, with the remaining level not sufficient for rice production. It is recommended, therefore, that application of supplemental organic fertilizers be done when using the rice-pepper-corn relay, ricemungbean-mungbean+corn, rice-onion-mungbean+corn and ricemungbean-mungbean+corn cropping patterns. The potassium is still sufficient to sustain the succeeding crops. Economic profitability Rice-pepper-corn relay cropping obtained the highest net income (P110,346/ha/year) in Aracua, Batac, Ilocos Norte. The high yield of pepper contributed to the overall high net income of the whole cropping pattern. The net incomes of rice-corn-onion (P83,796) and rice-onion-mungbean+corn relay (P82,963) were almost similar. Onion contributed the most to the overall net income of the cropping patterns. Lowest net incomes were soil properties. To compensate, a more profitable second crop should be planted. In terms of production costs, rice-corn-onion incurred the highest (P73,836/ha) followed by rice-onion-mungbean+corn relay (P69,674) and rice-pepper-corn relay (P63,063/ha. Pepper production incurred the highest expense in the rice-pepper-corn relay-cropping pattern. On the other hand, onion production had the highest production cost in the rice-onion-mungbean+corn relay and rice-corn-onion patterns. Based on the marginal earnings per cropping pattern, the rice-pepper-corn relay pattern obtained the highest earnings (Figure 3). The marginal earning of 1.75 implies that one peso and seventy-five centavos (P1.75) was earned for every P1.00 invested in the pattern. Farmers with more capital could adopt and invest in the pattern. Rice-mungbean+corn-corn obtained the lowest marginal earning (P0. 98). The five cropping patterns are suited under Batac and Currimao conditions based on the agro-climatic indices. Their obtained from rice-mungbean-mungbean+corn (P52,719/ha) and rice-mungbean+corn-corn (P53,227). This implies that mungbean is not a profitable crop. However, it should be included in the cropping patterns and is recommended as a third crop to improve profitabilities, however, vary due to the market value differences of the crop commodities. In Currimao, rice-corn-onion obtained the highest net income with P107,894/ha followed by rice-onion-mungbean+corn pattern PC Alquiza et al 17

6 (Figure 4). Rice-corn-onion pattern had relatively higher net income in Currimao than in Batac. The higher net income in Currimao was contributed by corn, the difference being that it was sold as green corn. Rice-mungbean-mungbean+corn in Currimao obtained the lowest net income (P67,225/ha/year). Trials in Bacnotan, La Union The weather data of PAGASA Vigan City was the basis for the development of planting calendars for Bacnotan, La Union. Based on the data, the planting of rice should start during the month of June when there is abundant rainfall. The slight rainfall occurring thereafter favors the growth and development of the rice crop. During the tillering up to early reproductive stage (July to August) rainfall is abundant, which favors weed control while providing sufficient water for the crop. Rainfall then decreases until the fourth week of September to October, which favors harvesting and drying. During the 3-year duration of the project, upland crops like mungbean, pepper, onion and corn. These months are favorable for growing crops because there is enough sunshine for the plants to manufacture their own foods. Likewise, October to December and January to April are periods of favorable dry weather for harvesting upland crops. The findings suggest that the rainfall data from Vigan City can be used for Bacnotan and areas in Ilocos Sur with a similar ecosystem. This further suggests that the planting calendars of the 5 cropping patterns in Bacnotan are fitted to the agro-climatic conditions and water availability in the area. The farmers can therefore follow the planting calendars for the crops in those patterns. Rice-corn-onion obtained the highest net income with P134,497/ha/year followed by rice-onion-mungbean+corn with P89,620/ha/year. Farmers in Bacnotan were previously planting only 2 crops a year, with corn as the second crop. The establishment of rice during the month of June increased the number of crops planted per year. The third crop added in the the planting calendars of the 5 cropping patterns were appropriate for the purposes. In most cases, the planting schedules of the different crops avoided the occurrence of typhoons during the rainy season and drought during the dry months of the year. The period from October to December favors the planting of system increased the net income (Figure 5). With the agro-climatic information and data on groundwater availability, the farmers were able to increase cropping intensity from 2 to 3 crops per year. The introduction of alternative crops in the cropping systems provided the farmers more choices of crops 18 Planting Calendars: Development Based On Agro-Climatic Indices

7 for planting in the area. SUMMARY & CONCLUSION The optimized planting calendars of 5 cropping sequences were developed based on agro-climatic indices, water availability and the avoidance of pests and adverse conditions. The study was established in Aracua, Batac, Ilocos Norte and conducted for 3 years, and then validated/verified during 2001 in Currimao, Ilocos Norte and 2002 in Bacnotan, La Union. Groundwater availability, soil fertility status and occurrence of insect pests and diseases were monitored. Profitabilities of the different cropping patterns were determined. Based on the findings, sowing for rice in Ilocos Norte is recommended from the fourth week of May to the second week of June, the onset of the rainy season. The crop will then be sustainable source of groundwater for irrigation, such as in the demonstration sites in Batac and Currimao in Ilocos Norte and Bacnotan in La Union, a third crop can also be planted between the second and third week of February to be harvested between April and the second week of May. Among the five planting calendars developed, rice-peppercorn set for June to May gave the highest net income of P110,346/ha/year in Batac, Ilocos Norte. In Currimao, Ilocos Norte, rice-corn-onion grown from June to April provided the highest net income (P107,894/ha/year). The rice-corn-onion raised from June to April gave the highest net income (P134,497/ha/year) in Bacnotan, La Union. The continuous rotation of crops probably suppressed the populations of insects and disease vectors as well as the growth of weeds. In rainfed areas, the groundwater can still support crop harvested between the fourth week of September and second week of October. The second crop can be planted between the second week of October and the second week of November. The second crop can be harvested between January and February, depending on the maturity of the crops. This period favors harvesting due to high dry weather harvest reliability. Corn, pepper, onion or mungbean can be planted as second crop. With production from January to March. Mulching and other water conservation techniques can farther extend planting up to May. A significant decrease in the amount of soil organic matter content was observed with continuous cropping. To solve the problem, supplemental application of organic fertilizers is recommended to make the soil sustainable for crop production. PC Alquiza et al 19

8 LITERATURE CITED Francisco SR Risk reference and optimum cropping pattern for rainfed areas of Ilocos. Philippine Journal of Crop Science 20(1): IRRI Proceedings of the Rainfed Lowland Rice Farming Systems Research Planning Meeting, Manila Ganotisi NDR, Castro RC, Alquiza PC & Maloom JM Agro-climatic characterization of the rice and rice-based areas of Ilocos. Unpublished 20 Planting Calendars: Development Based On Agro-Climatic Indices