INFLUENCE OF IRRIGATION REGIMES, ORGANIC FERTILIZER ON FORAGE YIELD OF DIFFERENT INTERCROPPING PATTERNS UNDER CALCAREOUS SOIL CONDITION.

INFLUENCE OF IRRIGATION REGIMES, ORGANIC FERTILIZER WITH DIFFERENT INTERCROPPING PATTERNS OF PEARL MILLET AND COWPEA ON FORAGE YIELD UNDER CALCAREOUS SOIL CONDITION.

Zizy M.Abbas^-1and A.A. Sallam^-2.

1-Forage Crops Research Department, Field Crops Res. Inst., ARC, Giza, Egypt

2-Water Requirements and Field Irrigation Research Department; Soils, Water and Environment Research Institute (SWERI); Agricultural Research Center (ARC); Egypt.

Key Words: Pearl millet, cowpea, crop patterns, compost, irrigation water quantities, water utilization efficiency

ABSTRACT

A filed experiment was conducted at the experimental farm of Nubaria Agricultural Research Station (30° 54´ N, 29° 57´ E, and 25m above sea level), Agricultural Research Center (ARC), Ministry of Agriculture and Land Reclamation (MALR), El-Behiera Governorate, Egypt, during 2016 and 2017 seasons. The objective of this investigation amid to study the effect of three water regimes (100%, 80%, and 60% ET_o), two compost rates (0  and20m³fad^-1),and five intercropping  patterns( Millet sole stand, cowpea sole stand , millet/cowpea 1:1, 1:2, and 2:1patterns) on some growth traits, forage yield, protein percentage, amounts of applied irrigation water and water utilization efficiency in calcareous soils.

Results can be summarized as follows:

1. Water regimes, compost rates and intercropping patterns significantly affected the tested growth traits, forage yield, and protein percentage.
2. Maximum values of studied traits were obtained with irrigation by 100% ET_o, while minimum values were recorded with irrigation by 60 % ET_o.
3. All growth traits, and yield, except for protein% were increased significantly due to applying compost compared with the control.
4. Growing of pearl millet with cowpea significantly increased plant height than sole cropping, and increased the number of tillers of pearl millet, while the increases of cowpea branches reached maximum number under sole cropping.
5. Water utilization efficiency reached the maximum values under 80% ET_o compared with the other two regimes.

INTRODUCTION

The lack of green forage during summer period is a great problem in Egypt especially in the new   reclaimed areas. Introducing some fodder species which have a wide adaptability to climatic and edaphic factors and good forage quantity and quality is very important to face the forage deficiency during this period (El –Toukhy 2008).Intercropping pearl millet   (Pennisetum glaucum) and   Cowpea (Vignaun gucilata L.) make  good utilization of all resources to sustain forage production in such calcareous soils. Among the advantages of intercropping grass – legume is they produce dry matter and nitrogen yield from unit area of soil more than that from monoculture of grass or legume due to more efficient utilization of different available growth elements. Barik et al (1996) revealed that Sorghum and Groundnut at 2:1 planting ratio significantly produced higher combined dry matter yield. Shata et al (2007) concluded that intercropping of cowpea with corn significantly affected grain yield and improved yield of millet when intercropped with cow pea than these of pure stand. Moreover El –Toukhy (2008) reported that the highest forage yield were obtained from pearl millet and guar at 3:1 planting ratio compared by sole planting.

The newly reclaimed calcareous soils at west of Alexandria are about 100,000 ha. Great efforts have been undertaken to solve soils problems, i.e. hardness of soil surface, compaction of surface layer, less organic content, low availability of phosphorus and micronutrients, physical and chemical properties. One of such efforts depends on the application of organic manure, as a soil amendment which reduce crusting and high soil temperature in summer season. It also supply some essential nutrients to the growing plants over a wide range of PH which interns increase forage productivity (Follett et al.,1981). Romero et al.(2000) reported that compost application provided energy for microorganism activity and increase the availability of N,P and K.

Water stress is one of the main problems in arid and semi arid areas. Lack of water influences most plant physiological processes, such as photosynthesis, photosynthetic material transmission to seeds, cellular development and transmission of nutrient in plants Davis et al.,(2007). Bonde et al. (2004) indicated that the addition of compost increased the availability of micronutrients in soil.

Irrigation is the most effective factor which limits increasing productivity of forage crops, as well as affecting fresh, dry and quality of forage production, i.e. crude protein yield, under newly reclaimed soil conditions. Recently, there are major problems from insufficient water to cultivate the cropped areas and to reclaim new lands to meet the growing population all over the world. Therefore, many efforts are practiced to increase water use efficiency with the limited water resources for irrigation. One of these methods is applying the deficit irrigation technique, e.g. applying less amount of water, considering minimum effect on crop productivity.

The main target of the present research is to study the influence of water stress treatments and compost rates on forage growth parameters and yields of different cowpea/pearl millet patterns, amounts of applied water, and water utilization efficiency under newly reclaimed calcareous soil conditions.

MATERIALS AND METHODS

Experimental site:

A field experiment was carried out at Nubaria Agricultural Research Station, Al-Behaira Governorate, Egypt, during the 2016 and 2017 summer growing seasons. The objective of this investigation was to evaluate the effect of three levels of irrigation water (100,80, and 60% ET_o); two rates of compost (with & without) and pearl millet/cowpea intercropping patterns on forage yield, quality, amounts of applied water, and water utilization efficiency under newly reclaimed calcareous soil conditions.

Soil samples were collected from two depths (0-30 and 30-60cm) to determine the main physical and chemical soil properties at the experimental site. The soil physical parameters (particle size distributions and soil texture class) were determined according to the FAO (1970), soil-moisture constants (soil field capacity (FC), wilting point(WP), and available soil moisture(ASM)were determined on mass basis by a pressure extractor apparatus), and soil bulk density(BD) values were determined in undisturbed soil samples using the core method and soil hydraulic conductivity was measured by (Black and Hartge, 1986). The soil chemical parameters (electrical conductivity (EC), soil reaction (pH), cations, and anions concentrations) were determined according to Page et al. (1982).The main physical and chemical properties of the soil at the experimental site are listed in Tables 1 and 2.

Table (1): The determined physical properties of the soil at the experimental site before plantingof the soil at the experimental site.

Table (2):Main chemical properties of the soil at the experimental site before planting.

Experimental design and studied treatments:

Split-split plot experimental design with four replicates was used to implement the field experiment. Irrigation water levels were assigned to the main plots, the compost fertilizer rates were in the sub plots, and the intercropping patterns occupied the sub-sub plots.

The studied treatments were:

A-    Levels  of irrigation water :

1-      100% ET₀ (I₁).

2-      80% ET₀ (I₂).

3-      60% ET₀ (I₃).

B-    Organic fertilizer  (compost ratios ):

1-        Without compost (B₁).

2-        20 m³ fad^-1 compost (B₂).

C-    Intercropping  patterns :

1-      Cowpea as sole crop (C₁).

2-      Pearl millet as sole crop (C₂).

3-      Cowpea 1:1 Pearl millet (C₃).

4-      Cowpea 1: 2 Pearl millet (C₄).

5-      Cowpea 2: 1 Pearl millet (C₅).

Cultural practices:

Seeds of pearl millet and cowpea were obtained from the Forage Research Department, Field Crops Research Institute, Agricultural Research Center, Giza, Egypt. Seeds were broadcasted at a rate of 20 and 16 kgfad^-1 for cowpea and pearl millet, respectively. Sowing dates were 15^th of May 2016 and 5^thof May 2017 growing seasons  .Commercial compost was applied at two rates of 0 and 20 m³fad^-1during the soil tillage before planting.The plot area was 24 m² (4 m width and 6 m length).Compost analysis (Table 3)was done according to the standard methods as described by Brunner and Wasner(1978). All plots in this experiment were fertilized with 100 kg N fad^-1 (as ammonium nitrate, 335 g N kg^-1), 100 kg P fad^-1 (as calcium super phosphate, 155 g P₂O₅ kg^-1), and 50 kg K fad^-1(as potassium sulphate, 480 g K₂O kg^-1). The N fertilizer was applied in three equal doses. The first dosage involved an application of 30% of N at the first irrigation, the second and the third dosages involved an application of 35% of N at first and second cutting, respectively. The P fertilizer was applied during land preparation. The K fertilizer was applied once at the second irrigation. All fertilizers were applied by surface broadcasting method. The other farming practices were done following the common practices at the Nubaria station.

Table (3): Some chemical properties of applied compost

Source :Arab Organization for Industrialization.

Three cuts were taken, the first at 45 days from sowing date and the others after 35 days from the first and the second cuts.

Data recorded:

In each cut, a sample of ten plants of crops under study from each plot was taken at random to measure the following :

1-   Plant height (cm) from soil surface until end of plant.

2-   Number of tillers for pearl millet or branches for cowpea per plant.

3-   Fresh and dry forage yields (t fad^-1).

4-   Crude protein percentage (CP, %): N content in forage was determined by Micro Keldahl method (A.O.A.C., 1980) and the crude protein (%) was obtained by multiplying N content by a factor of 6.25.

5-   Digestible protein (%) = (0.9596  x CP% -3.55)as reported by Bredon et al.(1963).

Crop-water relation:

-          Reference Evapotranspiration (ET₀):

 The ET₀values were calculated using CROPWAT program based on the agro-climatic data of the  local area are  presented in Table (4).

Table (4): Monthly average agro-climatic data and the calculated ETo values at the experimental site .

Amounts of irrigation water (AIW):

The AIW were calculated according to the equation given by Vermeiren and Gopling (1984) for drip system as follows:

where:

AIW = Depth of applied irrigation water (mm).

ET_o = evapotranspiration (mm day^-1).

Kr = Reduction factor, depends on ground cover, a value of 1.0 was used (where the spacing between drip lines is less than 1.8 m, FAO,56).

I = Irrigation intervals (days).

Ea = Irrigation efficiency of the drip irrigation system, an average value 0.8 was used as determined in the beginning of each season (Ismail, 2002).

LR = Leaching requirements (the leaching fraction was not considered in this experiment to avoid the effect of excess water on the stress treatments ).

Based on the actual emitter discharges, the irrigation time was calculated according to the equation given by Ismail(2002) as follows:

where:

t           = irrigation time (h).

A         = wetted area (m²).

q          = emitter discharge (m³/h).

AIW    = depth applied irrigation water (mm).

Water utilization efficiency (WUtE): The WUtE values were calculated according to Jensen (1983) as follows:

Statistical Analysis:

Data were statistically analyzed according to Snedecor and Cochran (1980) and treatment means were compared by least significant difference test (LSD) at 0.05 level of significance. Bartlett'^s test was done to test the homogeneity of error variance. The test was not significant for all assessed traits, so, the two season's data were combined.

RESULTS AND DISCUSSION

A. Growth traits and Yield

A.1.Effect of irrigation regimes on:

A.1.1.Growth traits:-

Data in Table (5) revealed that irrigation regimes had significant effect on plant height and number of tillers or branches plant^-1for pearl millet and cowpea respectively. The highest values of plant height at all cuts for the two crops under study were obtained from irrigation by 100% ET₀.The same trend was observed with number of tillers or branches. These results could be due to irrigation by 100% ET₀ supplied sufficient soil moisture in root zone which increased the capacity of plants in photosynthesis and then increased plant height and number of tillers or branches plant^-1. These results confirm the finding of El-Noemani et al. (2015) reported that plant height and no. of branches were increased by increasing water application level on bean plants .

A.1.2. Fresh and dry forage yields (ton fad^-1):

Irrigation regimes affected significantly  the total fresh and dry forage yields  Table ( 6) .The highest values were obtained with irrigation 100% and comprised 57.56 and 12.17ton fad^-1of the total fresh and dry yields ,respectively .The total fresh and dry yields were reduced by  60% of fresh and 41% of dry yield with 60% ET₀ as compared with irrigation 100%ET₀. These findings are in agreement with Rizk et al.(2011)who found that increasing water stress decreasing fresh and dry forage yields of cowpea ,pearl millet and sorghum. Also these finding were in harmony with Zegada et al (2006) on cowpea and pearl millet.

A.2. Effect of compost fertilizer on:

A.2.1. Growth traits

Results in Table (5) showed that plant height and no. of tillers or branches plant^-1were increased by compost application but did not reach the significant level with plant height, while no. of tillers or branches plant^-1were increased significantly. These results may be due to the role of compost as being a source of nutrient in increasing soil fertility which consequently increased the growth of pearl millet and cowpea. These results are in agreement with those obtained by Qamar et al .(2000) who found that no. of tillers plant^-1 of pearl millet  increased significantly with FYM application over control. Venderame et al. (2005) who reported that using compost had positive effect on growth traits. Also EL-Toukhy (2008) on pearl millet and guar .This might be related to improvement in physical conditions of the soil provided energy for microorganism activity and increase the availability and uptake of N,P and K which were positively reflected on growth.

Table

(5): Effect of irrigation regimes (I),compost (B) and intercropping patterns (C) on growth traits (combined over two seasons).

I=irrigation regimes(I₁=100%,I₂=80% ,I₃=60% ET₀)-B =compost (B₁=0, B₂=20m³fad^-1) –  C = Intercropping patterns (C₁=sole cowpea ,C₂= pearl millet, C₃= 1:1,C₄=1:2 ,C₅= 2:1( cowpea: pearl millet)).

A.2.2. Fresh and dry forage yields (ton fad^-1):

Data in Table (6) illustrated the significant effect of compost addition on fresh and dry yields. Relative increases percentage in total fresh and  total dry yields due to compost application at 20 m³fad^-1 as compared to control treatment were 20% and  36.5% ,respectively .The obtained  results are in agreement with those obtained by Hussain et al.(2001) who reported that compost is rich source of nutrients with high organic matter content and use of compost can be beneficial to improve organic matter status .Physical and chemical properties of soil can be improved by  using compost, which may ultimately increase  crop yield . Similar results were obtained by EL-Toukhy (2008) .

Table(6): Effect of irrigation regimes (I),compost (B) and intercropping patterns (C) on fresh and dry yield ton fad^-1 (combined over two seasons).

I=irrigation regimes(I₁=100%,I₂=80% ,I₃=60% ET₀)-B =compost (B₁=0, B₂=20m³fad^-1) –  C = Intercropping patterns (C₁=sole cowpea ,C₂= pearl millet, C₃= 1:1,C₄=1:2 ,C₅= 2:1( cowpea: pearl millet)).

A3.Effect of intercropping patterns on:

A. 3.1.Growth traits:

Data in Table (5)  revealed the response of cowpea and pearl millet to intercropping patterns (1:1 ,1:2 ,2:1 Cowpea /Pearl millet,( C:M)as compared to pure stand for both plants at the three cuts. The results indicated that maximum plant height of pearl millet was obtained insole planting ,while cowpea plants reached the maximum values with  1:2 (C:M ) pattern  at the three cuts  . Cowpea gave more number of branches with pure stand than any intercropping pattern followed by 1:2 pattern at the three studied cuts. While , pearl millet  gave the maximum number of tiller with 1:2 (C:M)intercropping pattern .In this concern, the enhancement of productivity by intercropping legume crop could lead to the increase of crop growth  ,which could be attributed to the advantage of legume/cereal intercropping and to better utilization of natural resources such as water, light and nutrients. Similar results were reported by Ntoukam et al.(1993)on cowpea and EL-Sarag (2013) on cowpea and sorghum.

A.3.2.Fresh and dry forage yields ton fad^-1:

Data in Table (6) revealed that the superiority of total fresh and dry forage yields of pearl millet (50.8 ton fad^-1) and (11.45 ton) was achieved from pure stand followed by 1:2 (C: M) intercropping pattern  ( 42.09 ton )and (8.65 ton) for the fresh and dry yield , respectively.  The increases forage yield of pearl millet at all cuts or total yield fad^-1., of solid planting may be due to pearl millet is good in producing a lot of fresh and dry matter. The same trend for cowpea it reached the maximum values of yield obtained with sole planting, where 1 C:2M pattern was superior when compared with other intercropping patterns  for total yield of individual cut and total cuts. The improving effect of intercropping cowpea with pearl millet on forage yield may refer to the ability of cowpea as legumes in soil nitrogen fixation which reflects on fresh plant, plant height and number of tiller or branches for both itself and pearl millet EL-Sarag (2013) and Naveed et al.(2018)on cowpea and pearl millet.

A.4.Interaction effects on:

A.4.1. Growth traits

Results of plant height and no.of tillers or branches as affected by the 1^st and 2^nd order interactions are presented in Table (7). Results indicated significant interactions on the above mentioned traits. The significant effects of these interactions on the studied growth traits means that the effect of studied levels of each of the studied factors does not behave the same under the different levels of the other factors. For example ,it is clear from the data that the increases in plant height and no. of tillers or branches plant^-1with increasing the irrigation regimes was greatly higher when 100%ET₀ was applied with compost if compared with that of without compost fertilizer treatment. These results are in agreement with Mousa et al (2017) who indicated that the interaction between irrigation levels and compost level increased growth traits on Egyptian clover .Similar trends were noticed with irrigation rates and intercropping patterns interaction, the increases in no. of tillers or branches plant^-1 with 1 :2 (C:M) pattern  was greatly higher under irrigation rate 100% ET₀ if compared with that of 60%ET₀ , but without significant different with that irrigated by 80%ET₀  this may be referring  to the positive response of pearl millet to nitrogen fixation from cowpea roots under moderate water stress ,El Sarag (2013).

It is clear from the results that the response of plant height and no. of branches to 1:2 (C:M) intercropping pattern without compost fertilizer application were significantly lower than those recorded with compost application.

Results of plant height and no. of tillers or branches plant^-1 as affected by interaction between irrigation levels, compost application and intercropping patterns are presented in Table (8). It is clear from the results that the increases in plant height and no. of tillers or branches plant^-1under the highest irrigation levels (100%ET₀) and compost application (20m³fad^-1) with 1:2 (C:M) intercropping pattern were significantly higher than those recorded with other treatments.

Table (7): Interaction effect of irrigation regimes (I), compost (B) and intercropping patterns (C) on growth traits (combined over two seasons).

I=irrigation regimes(I₁=100%,I₂=80% ,I₃=60% ET₀)-B =compost (B₁=0, B₂=20m³fad^-1) –  C = Intercropping patterns (C₁=sole cowpea ,C₂= pearl millet, C₃= 1:1,C₄=1:2 ,C₅= 2:1( cowpea: pearl millet)).

Table

 (8): Interaction effect of irrigation regimes (I),compost (B) and intercropping patterns (C) interaction on growth traits (combined over two seasons).

I=irrigation regimes(I₁=100%,I₂=80% ,I₃=60% ET₀)-B =compost (B₁=0, B₂=20m³fad^-1) –  C = Intercropping patterns (C₁=sole cowpea ,C₂= pearl millet, C₃= 1:1,C₄=1:2 ,C₅= 2:1( cowpea: pearl millet)).

A.4.2. Fresh and dry forage yields (ton fad^-1)  :

Results of fresh and dry forage yields as affected by interaction between irrigation regime, compost application and intercropping patterns are presented in Tables (9 , 10 and 11).The statistical analysis showed significant differences in fresh and dry forage yields due to the tested treatments. It is clear from the results that, the increases in fresh and dry yields with the highest irrigation level (100% ET₀) was greatly higher when compost was added as compared with that without compost, as well as with the 1:2 (C:M) intercropping pattern  if compared with other treatments .

Similar trends were noticed with the interactions between irrigation regimes and   intercropping pattern, compost and intercropping pattern, irrigation regimes, compost and intercropping patterns.

Table(9):Interaction effect of irrigation regimes (I),compost (B) and intercropping patterns (C) on fresh and dry forage yields                 ( ton fad^-1) (combined over two seasons).

I=irrigation regimes(I₁=100%,I₂=80% ,I₃=60% ET₀)-B =compost (B₁=0, B₂=20m³fad^-1) –  C = Intercropping patterns (C₁=sole cowpea ,C₂= pearl millet, C₃= 1:1,C₄=1:2 ,C₅= 2:1( cowpea: pearl millet)).

Table (10): Interaction effect of irrigation regimes (I),compost (B) and intercropping patterns(C)on fresh yield                            (ton fad^-1) (combined over two seasons).