Irrigation Scheduling of Drip Irrigated Capsicum Grown under Protected Cultivation ABSTRACT

Transcription

1 Irrigation Scheduling of Drip Irrigated Capsicum Grown under Protected Cultivation S.R. Bhakar 1, Chitra Shukla 2, S.S. Lakhawat 3 and K.K. Yadav 4 ABSTRACT The reported study was carried out to determine the crop water requirement and to develop irrigation schedule for capsicum (Capsicum annum L.) at plasticulture farm, CTAE, Udaipur, Rajasthan. There are four small structure of size 64 m 2 (16 4 mm) area each. Structure-1 is fully covered with 75% shadenet, structure-2 is fully covered with 40 mesh insectnet, Structure-3 covered with 200 micron LDPE UV stabilized sheet air vent on side and top provided with 75 % shadenet, and Structure-4 is covered with 200 micron LDPE UV stabilized sheet and air vent on side and top provided with insectnet. Before, growing capsicum crop the water requirement for capsicum crop was calculated by FAO- 56 method by using last 5 year i.e., 2008 to 2012, climatic data, collected from metrological observatory CTAE Udaipur. It was found mm or lit. for each structure during entire crop period. Schedule to irrigate capsicum under each structure was done that 1000 lit of water will be supplied to the crop total 51 times during the crop period. Crop evapotranspiration was determined by soil moisture balance method. Crop evapotranspiration was to be mm, mm, mm and mm for Structure-1, Structure-2, Structure-3 and Structure-4 respectively. Based on crop evapotranspiration, crop area, percent wetted area and emission uniformity of drip system, irrigation water requirement was determined, it was estimated as mm, mm, mm, and mm under each structure. The crop water requirement for outside condition was calculated by FAO 56 method, it was mm for entire crop duration. On the basis of estimated water requirements for different structures, an irrigation schedule is suggested for each structure and outside condition. Keywords: pepper, reference evapotranspiration, crop evapotranspiration, protected structures, crop coefficient. 1. Professor, Department of SWE, CTAE, Udaipur and corresponding author srbhakar@gmail.com 2. Chitra Shukla, M.Tech student, Department of SWE, CTAE, Udaipur 3. 3&4 Assistant Professor, Department of SWE, CTAE, Udaipur 1

2 INTRODUCTION The increasing global demand for food and other agricultural products calls for urgent measures to increase crop production per unit land used and per unit of water applied. Concerning this problem protected cultivation is scientific intervention through which production can be multiplied many times per unit land and per unit water. Capsicum cv. Indira botanically known as Capsicum annum placed in Solanceae family and classified as fruit vegetable crop. It is 6-10 months crop. One can take the production advisable to do the greenhouse farming. With the development of facility protected cultivation, more and more capsicum is grown in greenhouse to pursue the maximum economic profits. However, its cultivation is confined to warm and semi-arid countries where water is often a limiting factor for production (Dorjia et al., 2005). The crop grown under open conditions will not fulfill the export standards, so the search for new avenues has led to development of Hi-Tech precision agricultural systems. Greenhouse, the latest world in Indian agriculture is one such means, where the plants are grown under controlled or partially controlled environment resulting in higher yields than that possible under open conditions (Navale et.al., 2003) in capsicum. Protected structure is created locally by using different types of material. These structures are designed as per climatic requirements of the area for different sets of environmental conditions. Growing of capsicums under cover has been reported to give good quality produce with higher productivity in several countries. Recently, few entrepreneurs have started its cultivation under protected conditions like greenhouse; shade house etc. to get higher productivity and quality adopting the hybrids supplied by the private companies. Now a day apart from green color, other varieties like red, yellow, light green are also available. However, there is a need to assess the performance of capsicum hybrids under different structures. An exchange process between incoming energy and outgoing water occurs at the crop surface, which can be evaluated by an energy balance. Water is transferred out of the plant system as a result of satisfying this balance. This transfer process is called evapotranspiration (ET), which refers to the evaporation (E) of water from plant and soil surfaces and the transpiration (T) of water through the plant to the atmosphere. The combination of these processes is termed evapotranspiration (ET). One of the most 2

3 important components in agriculture is water and the main source of water is rainfall. In India, rainfall occurs during there are the four months viz. June, July, August and September. This duration of the rainy season however goes on decreasing from south to north and from east to west. In the extreme north-west it is barely two months. Estimation of irrigation water demand involves a computation of many water balance factors such as runoff, ground water table contribution, precipitation and evapotranspiration. The knowledge of evapotranspiration which includes evaporation of water from land surface and transpiration by vegetation is an essential aspect for estimating irrigation water requirements. The primary reason for irrigation is to provide water to a crop when the frequency and amount of rainfall is not sufficient to replenish water used by a crop system. Water requirements of the crop system depend on growth and development needs as well as environment demands. The levels of water used by the plant in growth and development are usually small compared to the atmospheric demands. Therefore, knowledge of the parameters involved with the water use process will help the irrigation scheduler to understand the driving force associated with water requirements of the crop. Evaporation and evapotranspiration are the most basic components of the hydrologic cycle. They affect the water balance from the time waterfalls upon the land as precipitation until the residual reaches the ocean. Evapotranspiration which includes evaporation of water from land and water surfaces and transpiration from vegetation continues to be of foremost importance in water resources planning and management. Evapotranspiration from vegetated surfaces is the result of several processes like radiation exchanges, vapor transport and biological growth operating within a system involving the atmosphere, plants and soil. Greenhouse farming, also known as protected cultivation, is one of the farming systems widely used to provide and maintain a controlled environment suitable for optimum crop production leading to maximum profits. This includes creating an environment suitable for working efficiency as well as for better crop growth (Aldrich and Bartok, 1989). 3

4 MATERIALS AND METHODS The experiment was carried out to study at plasticulture farm CTAE Udaipur. In this study the capsicum has been grown under four small size, naturally ventilated protected structures that is shednet house, insectnet house, poly house with shade net vents, poly house with insectnet vents, during February to July, 2013 at plasticulture farm CTAE Udaipur. The plant spacing followed was 50 cm x 30 cm. Experiment has been laid out in four small size structure of 16 m x 4 m size each. Each structure comprised of 400 plants of capsicum in four beds of 100 each. Irrigation was given through gravity fed drip irrigation system of 4 laterals in each structure. The crop was taken during 29 January 2013 to 15 July Experimental Site The experiment was carried out during the year 2013 at the Plasticulture Farm of College of Technology and Engineering, MPUAT Udaipur (Rajasthan). Udaipur is situated in the southern region of Rajasthan and at Longitude E and Latitude N at an Altitude of meters above the mean sea level. Agro-Climatic Conditions Udaipur comes under sub-humid agro-climatic region. It receives an average annual rainfall of mm, most of the received during the period of July to September. May is the hottest and December is the coolest month of the year. The maximum temperature goes as high as 46 C during summer and minimum as low as 5 C during winter months. The atmospheric humidity ranges from during June to October. Four types of raised arch shaped structures were used for studyi. Structure covered with shade net: Fully covered by shade net ii. iii. Structure covered with insect net: Fully covered by insect proof net. Structure covered with 200 µ LDPE polythene and natural ventilation through shade net: Top of the structure covered by polythene sheet, side opening and top vents covered by shade net with provision of 1.0 m wide apron from the ground. 4

5 iv. Structure covered with 200 µ LDPE polythene and natural ventilation through shade net: Top of the structure covered by polythene sheet, side opening and top vents covered by insect net with provision of 1.0 m wide apron from the ground. Growth stages Four growth stages were considered. They were the initial stage, developmental stage, midseason stage, and late season stage. The initial stage excluding seedlings at the nursery lasted for 21 days (January 29 February 18, 2013). The developmental growth stage lasted for 49 days (February 19, April 7, 2013). The mid-season growth stage (flowering and fruiting) stage lasted for 70 days (April 8 June 18, 2010) and the late season stage lasted for 28 days (June 19 - July 15, 2013). The entire crop period was of 168 days. This stage was later characterized by senescence and drying of leaves after the harvesting was over. Irrigation Scheduling based on Climatic Parameter of Different Structure Measurement of soil moisture The available soil moisture content at which irrigation should be applied is a good criteria as it indicates moisture status of the soil and its availability to plants. Many research workers studied these criteria and for capsicum it has been suggested to apply irrigation when 40 percent available soil moisture (ASM) is depleted (i.e. when ASM is 60 percent). The amount of water that is held by a certain mass of soil was calculated on weight basis and can be expressed as Soil moisture content % by weight = (weight of moist sample) (weight of dry sample) 100 (weight of dry sample) The soil samples at different depths have been taken with the help of soil auger and the average soil moisture will be determined by gravimetric method regularly throughout the growing period of capsicum for each structure having the irrigation schedule as per soil moisture depletion. From the point of view of irrigation the root zone depth considered at different stages are required. The soil moisture has been recorded as determined by the gravimetric method. When the soil moisture content depleted by 1000 lit; irrigation have been made to bring it to back up to field capacity. 5

6 ASM content = (Field capacity Permanent wilting point) BD RD 100 It was concerned that a common irrigation applied to all the climate controlled structures. The soil moisture depletion method is usually employed to determine the consumptive use of irrigated field crops. This study involves measurement of soil moisture from various depths at a number of times throughout the growth period. Consumptive use (Cu/ET) is calculated from the change in soil water content in successive samples from the following relationship: Where, n u = M 1i M 2i. A 100 i. D i i=1 u = water use from the root zone for successive sampling period or within one irrigation cycle (mm) n = number of soil layer sampled in the root zone depth D. M 1i = soil moisture percentage at the time of the first sampling in the i th layer. M 2i = soil moisture percentage at the time of the second sampling in the i th layer. A i = apparent specific gravity of the i th layer of the soil. D i = depth of i th layer of the soil (mm). Seasonal consumptive use (Cu= u) is calculated by assuming consumptive use values of each sampling interval. ASM = available moisture content, difference between field capacity and moisture percentage prior to irrigation. RD = depth of the root zone in cm, at different stages. The depth of irrigation will be converted in to volume of irrigation water applied per structure. The estimated volume of water has been applied to the structure with the help of calibrated tank. Water Requirement The water requirement of plants varies with time and depends on the season and growth of plants. It is essential to irrigate optimally during the stage of flowering to fruit maturity. Water 6

7 requirement of the plant will be evaluated to design the system and for that the following equation will be used. Where, W r Crop area ETc K E W r = peak water requirement, (lit day -1 plant -1 ) u c W a Crop area = row to row spacing (m) plant to plant spacing (m) of the crop ETc = crop evaporation rate, (mm day -1 ) K c = crop coefficient W a = wetted area, (%) E u = emission uniformity of drip system, decimal Irrigation Scheduling Irrigation scheduling is the application of water to crops in the proper amount and at the proper time, resulting in maximum crop yield and minimum leaching of water and nutrients to the groundwater. Irrigation scheduling can be accomplished using a water-balance accounting method, by monitoring soil moisture deficit. The irrigation-decision support tool developed by the United Nations Food and Agriculture Organization (FAO) to estimate crop water requirements and to schedule irrigation has been used for deficit irrigation studies in Turkey, Morocco, and Pakistan (Smith et al., 2012). It is a one-dimensional volume-balance water model (CropWat, 2010), shown in Fig. 1, which solves the water balance equation: Sm = R + I ETc D Where R = rainfall (mm) I = irrigation (mm) D = drainage (mm); Etc = crop evapotranspiration (mm) Sm = change in soil moisture (mm) Rainfall Irrigation Evapotranspiration Change in plant available soil 7 moisture

8 Water Requirement (lit/day) Root zone Drainage Fig.1 Diagram of one-dimensional irrigation scheduling model RESULT AND DISCUSSION Determine Water Requirement and Decide Schedule before growing crop on the basis of last 5 years data 2008 to 2012 Irrigation scheduling has been decided before growing of the crop by using the last five year data i.e to 2012 for the months January to July. The mean value of water requirement for the year 2008 to has been taken to decide the schedule for irrigation of the same crop. It has been found lit. for the whole growing period. The available capacity supply tank is 1000 lit. So, for the convenience of the supply of measured amount of water, it has been decided, after depletion of 1000 lit of water in the root zone of the crop, the irrigation will be provided. According to this, scheduling of irrigation has been done that 1000 lit of water will be supplied to the crop total 51 times during the crop period, 2 times in initial stage, 12 times in development stage, 30 times in mid season and 7 times in late stage. The interval between the two consecutive irrigation has been found 10 days in initial stage, 4 days in development stage, 3 days in mid season and 4 days in late stage under each structure. Water requirement is graphically represented in the Fig Days After Planting Fig.2 Mean water requirement for last five the year i.e Determine Water Requirement under Different Structures and Outside for 2013 and Decide Schedule for Irrigation 8

9 weekly water requirement (lit/day) Water Requirement under different structure and outside condition for the crop period have been calculated according to the equation given in previous chapter i.e. material and method, by using the daily climatic data under each structure. The total water requirement for the entire cropping period was calculated as lit, lit, lit, lit and lit for Structure-1, Structure-2, Structure-3, Structure-4 and outside respectively. The total water requirement of capsicum crop under different structure and outside condition have been calculated and depicted in Table 1. From the Table 1, it was found that the water saving under Structure-1, Structure-2, Structure-3, and Structure-4 were %, 19.32%, 23.34% and % respectively, compare to outside condition. The minimum water saving was observed under Structure-2, on the other hand maximum water saving was found under Structure-1. This is graphically represented in Fig.3. Total water requirement under different structure and outside for 2013 has been graphically represented in Fig Fig.3: Weekly water requirement under each structure and outside Table.1: Total Water Requirement of capsicum crop under different structure and outside condition Structures 1 Structure 2 Structure 3 Structure 4 Outside Standard Weeks Total Crop Water Requirement Treatment lit. mm Structure Structure Structure Structure Outside According to Iwena (2002), capsicum crop requires 1000 to 1500 mm of water during the 9

10 water requirement (mm) growing season. According to FAO (1999) however, when the crop is grown extensively under rain fed conditions, high yields are obtained with rainfall of 600 mm to 900mm, well distributed over the growing season. Huguez and Philippe (1998) also indicate that the total water requirements are 750 mm to 900 mm and up to 1250 mm for long growing periods and several pickings. The results obtained from the current study, compare quite well with those obtained by Iwena (2002), capsicum requires 1000 mm to 1500 mm of water during the growing season Structures 1 Structure 2 Structure 3 Structure 4 Different Growing Structures Outside Fig.4: Total water requirement under different structures and outside for 2013 Irrigation scheduling has been decided after growing of the crop on the basis of different climatic condition under each structure and outside of the structure. It has been found that 1000 lit of water should be supplied to the crop total 33 times under Structure-1, 40 times under Structure- 2, 38 times under Structure-3, 34 times under Structure-4 and 50 times for open condition during the entire crop period. For Structure-1, it has been found that 1000 lit of water will be supplied to the crop total 33 times during the crop period, 2 times in initial stage, 7 times in development stage, 21 times in mid season and 3 times in late stage. The interval between the two consecutive irrigation has been found 11 days in initial stage, 7 days in development stage, 3 days in mid season and 9 days in late stage. For Structure-2, it has been found that 1000 lit of water will be supplied to the crop total 40 times during the crop period, 2 times in initial stage, 10 times in development stage, 24 times in mid season and 4 times in late stage. The interval between the two consecutive irrigation has been found 10 days in initial stage, 5 days in development stage, 3 days in mid season and 7 days in late stage. For Structure-3, it has been found that 1000 lit of water will be supplied to the crop total 34 times during the crop period, 2 times in initial stage, 8 times in development stage, 24 times in 10

11 Water Requirement (lit/day) mid season and 4 times in late stage. The interval between the two consecutive irrigation has been found 10 days in initial stage, 6 days in development stage, 3 days in mid season and 7 days in late stage. For Structure-4, it has been found that 1000 lit of water will be supplied to the crop total 40 times during the crop period, 2 times in initial stage, 7 times in development stage, 21 times in mid season and 4 times in late stage. The interval between the two consecutive irrigation has been found 10 days in initial stage, 7 days in development stage, 3 days in mid season and 7 days in late stage. And for outside of the structure, it has been found that 1000 lit of water will be supplied to the crop total 50 times during the crop period, 3 times in initial stage, 10 times in development stage, 30 times in mid season and 7 times in late stage. The interval between the two consecutive irrigation has been found 7 days in initial stage, 5 days in development stage, 2 days in mid season and 4 days in late stage. This is depicted in Table 2. Water holding capacity and permissible depletion of moisture content of experimental field has been calculated as 7.83 cm and 3.92 cm respectively for 45 cm of root zone depth. It has been found that there will not be any adverse effect on crop growth and yield if the moisture content of root zone soil depleted upto lit per structure. The given irrigation intervals between two consecutive irrigation are suggested to the farmer for different structures and outside condition by considering this permissible moisture depletion value i.e lit per structure (64 m 2 ). The water requirement under Structure-1, Structure-2, Structure-3, Structure-4 and outside condition for the year 2013 has been graphically shown in Fig.5, Fig.6, Fig.7, Fig.8 and Fig.9 respectively Days After Transplanting Fig.5: Water requirement under Structure-1 for

12 Water Requirement (lit/day) Water Requirement (lit/day) Water Requirement (lit/day) Water Requirement (lit/day) Days After Planting Fig.6: Water requirement under Structure-2 for Days After Planting Fig.7: Water requirement under Structure-3 for Days After Planting Fig.8: Water requirement under Structure-4 for Days After Planting 12

13 Fig.9: Water requirement of outside the structure 13

14 Table.2: Developed irrigation schedule under different structure and outside condition for 2013 Structure-1 Name of Growth Length of Growing No. of Irrigation Interval ( days) Stages Period (days) Initial Development Mid-season Late Total Structure-2 Growth Stages Length of Growing No. of Irrigation Interval ( days) Period (days) Initial Development Mid-season Late Total Structure-3 Growth Stages Length of Growing No. of Irrigation Interval ( days) Period (days) Initial Development Mid-season Late Total Structure-4 Growth Stages Length of Growing No. of Irrigation Interval ( days) Period (days) Initial Development Mid-season Late Total Outside Growth Stages Length of Growing No. of Irrigation Interval ( days) Period (days) Initial Development Mid-season Late Total However the higher fruit yield per plant (1720 gm/plant) was recorded under Structure-4, which was significantly superior over the all growing structures while the lowest yield (1285 gm/plant) was recorded under Structure-1. 14

15 Table.3: Effect of different types of growing structures on quantity paramer of Capsicum cv. Indira Growing Individual fruit Fruit Fruit yield Fruit yield Structure weight (gm) yield/plant /sqm area (ton/ha) (gm) (gm) Structure Structure Structure Structure SE m CD (P=0.05) CV (%) SUMMARY AND CONCLUSIONS The crop evapotranspiration was determined under each structure by gravimetric method. The crop evapotranspiration for outside condition was determined by FAO 56 method. It was found that the crop evapotranspiration was mm for outside condition and under the Structure-1, Structure-2, Structure-3, Structure-4, it was like mm, mm, mm and mm respectively. It has been concluded that Structure-1 minimize crop evapotranspiration and it is lower by % than that of outside the structure. Similarly, the crop evapotranspiration is lower by %, % and % in comparison to the outside ET c, for Structure-2, Structure-3 and Structure-4 respectively. The maximum crop evapotranspiration was recorded under Structure- 2 and minimum under Structure-1. Before, growing capsicum crop the water requirement for capsicum crop was calculated by FAO-56 method. The last 5 year i.e., 2008 to 2012, climatic data was used for calculation, collected from metrological observatory CTAE Udaipur. It was found mm or lit for each structure during entire crop period. Schedule to irrigate capsicum under each structure was done that 1000 lit of water will be supplied to the crop total 51 times during the crop period, 2 times in initial stage, 12 times in development stage, 30 times in mid season and 7 times in late stage. The interval between the two consecutive irrigation has been found 10 days in initial stage, 4 days in development stage, 3 days in mid season and 4 days in late stage under each structure. The crop water requirement under each structure was determined by gravimetric method during the crop period. It was estimated mm, mm, mm, and mm under each structure. The crop water requirement for outside condition was calculated by FAO 56 15

16 method, it was mm for entire crop duration. It was concluded that the water saving under Structure-1, Structure-2, Structure-3, and Structure-4 were %, 19.32%, 23.34% and % respectively, compare to outside condition. The minimum crop water requirement was observed under Structure-1 ( mm), on the other hand maximum water requirement was found under Structure-2 ( mm). On the basis of estimated water requirements for different structures, an irrigation schedule is suggested for each structure as 1000 lit of water should be supplied to the crop total 33 times under Structure-1, 40 times under Structure-2, 38 times under Structure-3, 34 times under Structure-4 and 50 times for open condition during the entire crop period. The irrigation interval between two consecutive irrigation at initial stage (21 days) has been suggested as 11 days for Structure-1, 10 days for Structure-2, Structure-3, Structure-4 and 3 days for open condition. For development stage (49 days) it is suggested as 7 days for Structure-1, 5 days for Structure-2, 6 days for Structure-3, 7 days for Structure-4 and 5 days for open condition. For mid season stage it was suggested as 3 days for all four structure and 2 days for open condition. For late stage it was suggested as 9 days for Structure-1, 7 days for structure-2, structure-3, Structure-4 and 5 days for outside. On the basis of yield obtained and water saved inside each structure, Structure covered with polythene and natural ventilation through insect net was found most suited structure for capsicum crop in semi arid region. ACKNOWLEDGEMENTS: The expenses made in the study were given through AICRP on APA, MPUAT, Udaipur by ICAR, New Delhi. REFFERENCE Aldrich, R.A. and J.W. Bartok, Greenhouse Engineering. Northeast Regional Agricultural Engineering Service, Cooperative Extension, Ithaca, NY. Allen, R.G., L.S. Pereira, D. Raes and M. Smith, Crop evapotranspiration, guidelines for computing crop water requirements. FAO Irrigation and Drainage paper No. 56. FAO Rome, Italy: 300. Dorjia, K., M.H. Behboudiana and J.A. Zegbe-Dominguezb, Water relations, growth, yield, and fruit quality of hot pepper under deficit irrigation and partial rootzone drying. Sci. Hort. 104,

17 Huguez D. and Philippe De Leenor Ways of Water; Run-off, Irrigation and Drainage. 4 th Ed. Imperimie Guyot Braine-le-Chateau, Belgium. Iwena O.A Essential Agricultural Science for Senior Secondary Schools. Tonad Publishers Ltd., Ikeja. pp Navale A. V., S. B. Nandagude, A. G. Pawar, H. M. ghodke, and A. D. Bhosale, Comparative study of capsicum skirting and top covering effect in low cost greenhouse.in: Proc. All India Sem. Potential Prospects for Protective Cultivation Institute of Engineers, Ahmednagar, December 12-13, 2003, p